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United States 
Environmental Protection 
Agency 


Office of Research and 
Development 
Washington, D.C. 20460 


SEPA An Ecological 

Assessment 
of the Louisiana 
Tensas River Basin 



Classified Image - 
Vegetation Change 
1970s to 1990s. 


Land Cover 
Forest 
Forest Loss 
Forest Gain 
Human Use 
Water 


EPA/600/R-99/016 
February 1999 






Printed with Soy/Canola ink on paper that contains at least 50% recycled fiber and is recyclable. 



An Ecological Assessment of the 
Louisiana Tensas River Basin 

Daniel T. Heggem 1 , Anne C. Neale 1 , 

Curtis M. Edmonds 1 , Lee A. Bice 2 , 

Rick D. Van Remortel 2 , and K. Bruce Jones 1 


Environmental Sciences Division, U.S. Environmental Protection Agency, 
Las Vegas, Nevada 

2 Lockheed Martin Environmental Services, Las Vegas, Nevada 













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Table of Contents 


Executive Summary 

Chapter 1. Taking a Broader View 1 

Purpose and Organization of This Atlas 2 

Landscape Ecology and the Analysis of Broad-Scale Environmental Condition 3 

What are Landscape Indicators and How Do They Help to Understand Environmental Conditions'? 4 
How Were the Landscape Indicators Selected? 6 

How Were the Landscape Indicators Measured? 10 

How Were the Landscape Indicators Summarized? 12 

Chapter 2. The National Context 13 

Data Sources ^ 

How to Read the Maps and Charts in this Report 16 

Human Use Patterns 17 

Forest Patterns 

Patterns Affecting Water Quality 22 

National Context Summary 24 

Chapter 3 . The Tensas River Basin Landscape Assessment 25 

Biophysical Setting 25 

Land Cover 27 

Humans in the Landscape 28 

Population Density and Change 28 

Human Use Index 28 

Roads 29 

Roads Along Streams 30 

Forests in the Landscapes 30 

Percentage of Forest Cover 30 

Forest Fragmentation 33 

Percent of the Watershed in the Largest Forest Patch 33 

Detailed Forest Analysis of the Tensas River Basin, 1970 s to 1990 s 34 

Vegetation Change 30 

Vegetation Change by Subwatershed 37 

Forest and Crop Land Along Streams 36 

Water and the Landscape 40 

Watershed Indicators 41 

Riparian Analysis 42 

Vegetation Change Along the Tensas River Reach 43 

Backswamp Area Analysis 43 

Soil Erodibility Analysis 45 

Wetland Restoration Analysis 46 

Chapter 4 . Water Quality 55 

Nitrogen and Phosphorus Export to Streams 62 

Chapter 5 . Comments and Recommendations 63 


Appendix 


66 
























<\ 









EXECUTIVE SUMMARY 

TENSAS RIVER BASIN - A LANDSCAPE APPROACH TO COMMUNITY- 

BASED ENVIRONMENTAL PROTECTION 



These images illustrate the 12% decrease in total forested landcover between the early 1970s and the 

early 1990s. 

Tensas River Basin 


The purpose of this document is to give the results 
of an ecological assessment using landscape ecology and 
water quality methods in the Tensas River Basin, Louisiana. 
This assessment can be used as a tool to estimate the 
impact of human land use practices that are being currently 
implemented to improve environmental quality. It can be 
also used forecosystem targeting and help people make 
good decisions on the best location for restoration sites. 

The U.S. EPA’s Office of Research and Development, 
Landscape Ecology Branch did this work under the 
guidance of U.S. EPARegion 6, the Louisiana Department 
of Environmental Quality and the U.S. EPA Gulf of Mexico 
Program by way of the Regional Applied Research Program 
(RARE). 

The Tensas River Basin encompasses approxi¬ 
mately 930,000 acres of Mississippi River alluvial flood plain 
in Northeast Louisiana. Historically, most of the Basin was 
covered with bottomland hardwood forested wetlands. The 
bottomland hardwood wetlands of the Tensas River Basin 
have been described as some of the richest ecosystems in 
the country in terms of diversity and productivity of plant and 
animal species. At the same time, these cleared lands are 
recognized as some of the Nation’s most productive 


farmland for grain and fiber. The result is a conflict of land 
use between traditional row crop agricultural interests and a 
concern for a healthy, diverse, and stable ecosystem. 

The Tensas River Basin is a target watershed of 
several U.S. Environmental Protection Agency environmen¬ 
tal studies including the Nonpoint Source Management 
Program, U.S. EPA Region 6, and the Gulf of Mexico 
Program. The Nonpoint Source Management Program has 
identified watersheds in Louisiana which have been 
impaired by nonpoint pollution and where land use prac¬ 
tices contribute to these pollutant problems. This program 
identified specifically what types of best management 
practices need to be implemented to improve environmen¬ 
tal conditions. Using the existing data and with the 
cooperation of landowners, the Tensas River Basin offered 
a unique opportunity to implement best management 
practices that could help reduce the concentration of 
sediment, excess nutrients, or pesticides leaving the 
Basin. The nutrients leaving the Tensas River Basin, 
combined with other Mississippi Valley watersheds, are of 
concern to the Gulf of Mexico Program because research 
has shown that excess nutrients cause hypoxia (<2 mg/I 
oxygen) in the bottom waters of the Gulf of Mexico. This 












condition represents a threat to the coastal marine ecosystem 
and fisheries in this region of the Gulf. Landscape Ecology 
methods provide a tool to assess the impact of human landuse 
practices that are being implemented to improve environmental 
quality. 

In years past, the freshwater marshes, stream bank 
areas, and bottomland swamps of the Tensas River Basin were 
under strong development pressures. Large portions of forest 
near streams and in backwater swamp areas were converted to 
agriculture. This loss of forested areas decreased filtering 
capacity that normally removes pollution and nutrients before 
they enter streams, lakes, and estuaries. Wetland forests also 
dissipate energy and nutrients associated with extreme 
precipitation events and therefore reduce damage to down¬ 
stream farms and cities resulting from floods. The Tensas River 
Basin is unique in that natural levees along the riparian vegeta¬ 
tion lie on the highest ground in the Basin. This causes 
drainage water to run parallel to streams for many miles before 
actually entering the stream and river water channels. Wet¬ 
lands and backswamps then become the vegetation filtering 
areas for pollutants and nutrients. Preserving or restoring 
wetland forests have other economic benefits including wetland- 
based recreation, including hunting and harvesting wetland 
plants. The people who live within the Tensas River Basin 
realize that the vegetation along a stream and in backswamp 
areas can influence the condition of both the stream bank and 
the water in the stream. Restoration efforts began in the early 
1990s. 

The strip of vegetation along streams is known as 
the riparian vegetation zone. It is commonly described by the 
types of vegetation it contains and by the presence of water. 

In an ideal situation, many pollutants and fertilizers will be 
intercepted or absorbed by the riparian vegetation and it’s root 
system. This helps to keep the streams clean. Bank erosion 
is also mitigated by intact riparian vegetation. The conditions 
of the riparian ecosystem over a whole watershed can be 
studied in order to learn where, for example, a restoration 
project would most improve water quality. Similarly, a charac¬ 
terization of riparian conditions over the entire Tensas River 
Basin can help to identify which areas of the Basin are most 
likely to see improved water quality as a result of riparian 
vegetation improvements. 

Land cover is the product of past land uses on the 
backdrop of the biophysical setting. A map of landcover is 
essentially a picture of the dominant vegetative, water, or 
urban cover in an area. The images of land cover in the 
Tensas River Basin for 1972 and 1991 (see above) are based 
primarily on images taken by the Landsat Multispectral 
Scanner satellite since the early 1970s. The land cover map 
was based on the North American Landscape Character¬ 
ization (NALC) data, a Federal effort to create similar data for 
the entire oountry. The resolution of the land cover data is 60 
meters, so each pixel (picture element) represents an area 
about the size of a football field. Although individual 


pixels are far too small to be rendered accurately here, 
the visual impression of broadscale regional patterns is 
readily apparent. Forest vegetation shows up on the 
image as red in color, agriculture shows up as light red, 
grey, light blue and white and almost always shows a 
pattern with rows or right angles typical of farm fields. 

These images were then classified for landuse. 
The classifications were forest, human use (urban and 
agriculture) and water. Through the use of computerized 
Landscape analyses, the 1972 image was compared to 
the 1991 image and changes in forest areas and human 
use areas were calculated. As the images show, there 
was a tremendous forest loss over that time period. In 
1972 the land cover types forest and agriculture covered 
an area of about 34% and 65% of the area, respectively. 

In 1991 the land cover types forest and agriculture 
covered an area of about 22% and 77% of the area, 
respectively. Where forests have been removed, agricul¬ 
ture and urban land covers become more dominant, this 
can be seen by comparing the images to observe the 
forest loss over 20 years. 

The images also show how the forest, agricul¬ 
ture and urban landcover vary across the landscape of the 
Tensas River Basin. Understanding the variation of 
landcover with respect to landscape features, such as 
cities, roads, lakes and streams, is the foundation of the 
landscape ecological assessment. Other landscape 
indicators include: population density and change, human 
use index, roads, roads along streams, percentage of 
forest cover, forest fragmentation, percent of the water¬ 
shed in the largest forest patch, forest analysis of the 
Tensas River Basin, vegetation change, vegetation 
change by subwatershed, forest and crop land along 
streams, watershed indicators, riparian analysis, 
vegetation change along the Tensas River Reach, 
backswamp area analysis, soil erodibility analysis, and 
wetland restoration analysis. 

The Tensas River Basin is one of 2,099 individual 
watersheds located across the United States. Many 
people throughout the United States are restoring riparian 
vegetation areas and are in need of GIS and landscape 
methods to help them make good decisions on the best 
locations for restoration sites. 


An Ecological Assessment of the Louisiana Tensas River Basin Chapter 7 



Chapter 1: Taking a Broader View 



The Gulf of Mexico Program is working with its partners 
including U.S. EPA Regions 4,5,6, and 7 to identify ap¬ 
proaches to reduce nutrients in the surface waters of the 
Mississippi River System. The problem is being ad¬ 
dressed at the scale of the larger watershed (Mississippi 
River System). This report reflects the Landscape 
Ecology research done to characterize changing land¬ 
scape patterns as they relate to potential changes in 
nutrient loading for one river basin. This approach can be 
refined and applied to other watersheds within the Missis¬ 
sippi River System. 

Environmental quality is important to everyone. It affects 
our health, our quality of life, the sustainability of our 
economies, and the futures of our children. Yet pres¬ 
sures from an increasing population coupled with the 
need for economic development and an improved 
standard of living often result in multiple impacts on our 
natural resources. And, just as a person with a less- 
than-healthy life style is more prone to infection, a 
weakened ecosystem is less able to withstand additional 
stress. Unfortunately, it is often difficult to see these 
changes in environmental quality because they occur 
slowly or at scales we do not normally consider. 

There is growing public, legal, and scientific awareness 
that broader-scale views are important when assessing 
regional environmental quality. In the past, media 
attention has focused on dramatic events, focusing our 
environmental awareness on local or isolated phenom¬ 
ena such as cleaning up Superfund sites, stopping 
pollution from a drainage pipe, saving individual endan¬ 
gered species, or choosing a site for a parish landfill. In 
an era of environmental legislation, monitors of environ¬ 
mental quality responded to legal standards, like those 
for drinking water or air quality, and as a result they 
reported very narrow views of the environment. Given 
this view of the world, scientists studied fine-scale model 
systems and considered humans to be external factors. 
Today, our perceptions are changing. We realize that 
humans and our actions are an integral part of the 
global ecosystem, and that the environment is compli¬ 
cated and interconnected with human activities across 
local and regional scales. We have begun to take a 
broader view of the world and of our place in natural 
systems. 

Technology has advanced in ways that make it easier to 
obtain new views of overall environmental quality. 

Larger patterns and processes can be studied by using 
computers and satellites. These technologies, com¬ 
bined with a better understanding of how the pieces fit 
together, help to understand where we are now with 
regard to environmental quality, where we hope to be in 
the future, and what steps need to be taken to get there. 


This atlas takes advantage of some of these technolo¬ 
gies in assessing environmental conditions over the 
Tensas River Basin of Louisiana. 


Just as we now watch broad-scale weather patterns to 
get an idea of whether it will rain in the next few days, we 
can develop a better assessment of current environmen¬ 
tal conditions by combining regional and local-scale 
information. Broad-scale weather patterns are important 
because they affect and constrain what happens locally 
on any given day. By taking a broader view of the environ¬ 
ment, or widening our perspective about how the environ¬ 
ment is put together, it becomes easier to see where 
changes occur and to anticipate future problems before 
they materialize. 



Bottom-land Hardwood forest of the Tensas River Basin. 























□ 


An Ecological Assessment of the Louisiana Tensas River Basin Chapter 1 



Purpose and Organization of this Atlas 


This atlas presents an environmental assessment of 
the Tensas River Basin of Louisiana (Figure 1.1). 

The assessment was conducted by using measure¬ 
ments derived from satellite imagery and spatial 
data bases and summarized by subwatersheds. 

The information presented in this atlas is intended to 
help visualize and understand the changing condi¬ 
tions across the watershed and how this pattern of 
conditions can be used as a context for understand¬ 
ing community-level situations within the region. 


The atlas is divided into five chapters with one appendix. 
This chapter introduces the reasons for doing a broad- 
scale regional analysis of environmental condition. 
Chapter 2 places the Tensas River Basin into the context 
of the lower 48 states. Chapter 3 presents an analysis of 
landscape conditions in the Tensas River Basin and 
briefly explains the landscape analysis methodology. 
Chapter 4 discusses water quality issues in the Tensas 
River Basin. Chapter 5 presents some recommendations 
for future efforts. The Appendix provides additional data 
that could not be included in Chapters 3 and 4. 



Tensas River Basin 

Providence 


Scale 1:1,000,000 

0 5 10 15 


20 Kilometers 


Figure 1.1 




































_ - 


An Ecological Assessment of the Louisiana Tensas River Basin Chapter 1 


m 






Landscape Ecology and the Analysis of 
Broad-Scale Environmental Condition 


To most people, the term “landscape” suggests either a 
scenic vista or a backyard improvement project. To 
ecologists and other environmental scientists, a land¬ 
scape is a conceptual unit for the study of spatial 
patterns in the physical environment and the influence of 
these patterns on important environmental resources. 
Landscape ecology is different from traditional ecology in 
several ways. First, it takes into account the spatial 
arrangements of the components or elements that make 
up the environment. Second, it recognizes that the 
relationships between ecological patterns and processes 
change with the scale of observation. Finally, landscape 
ecology includes both humans and their activities as an 
integral part of the environment. 

There are many applications for landscape ecology and 
broad-scale information in regional assessments. For 
example, we can identify the areas that are most heavily 
impacted today by combining information on population 
density, roads, land cover, and air quality. In the Tensas 
River Basin, we already have good information (from the 
U.S. Census Bureau) about which areas are most urban¬ 
ized. But which areas have only a small proportion of 
stream length bordered by adjacent forest cover? Which 
areas are characterized by a 
high degree of forest fragmen¬ 
tation? What percentage of 
forest loss occurred on wet 
soils? What about informa¬ 
tion for watersheds instead of 
areas? Broad-scale mea¬ 
surements can be taken in 
order to make relative com¬ 
parisons of these indicators 
over the entire region. 


Another use of this approach 
is to identify the most vulner¬ 
able areas within the water¬ 
shed. Vulnerable areas are 
not yet heavily impacted, but 
because of their circum¬ 
stances they are in danger of 
becoming so. 


One example might be an area that has a relatively high 
percent of forest cover, but that is also experiencing rapid 
gains in human use of the land. Such an area might be 
more vulnerable to forest fragmentation than a similar 
area with less human use or less forest area. 

A third application of this approach is to place localities 
into a watershed and/or regional context. Some indi¬ 
vidual towns and rural areas in the Tensas River Basin 
may seem isolated, perhaps within a large forested area. 
However, all are connected by physical features and by 
ecological processes. Water flows from one place to 
another, roads provide a connecting infrastructure, and 
land cover patterns of forest and agriculture form a 
connected backdrop for all of our activities. While land 
management decisions are made and implemented at a 
local scale, a watershed perspective can guide our 
decisions and make us better stewards of our environ¬ 
ment. By placing our homes, farms, neighborhoods, and 
government organizations into a watershed landscape 
picture, we can begin to make informed decisions that 
consider not only our goals and actions, but our 
neighbor’s as well. 

















□ 


An Ecological Assessment of the Louisiana Tensas River Basin Chapter 7 


Figure 1.2 illustrates how a single community is linked to 
the landscape at several different scales and across 
different mapping units (watersheds and parishes in this 
example). Tallulah is highlighted in the middle of the 
figure. At this scale we concentrate on individual land 
parcels and roads, and our decisions are based on a 
local perspective. Broader-scale perspectives emerge as 
we follow the lines up either side of the figure. We see 
that the community is part of both a subwatershed (left) 
and a parish (right), which, in turn, are components of 
groups of watersheds and parishes. These larger groups 
are components of the entire region. This is an important 
concept because local environmental issues can have 
regional impacts. 


What are Landscape Indicators and How 
Do They Help to Understand Environmental Con¬ 
ditions? 

An indicator is a number that is calculated by summariz¬ 
ing data. The indicator calculations may also consider 
related data or use a model to improve reliability. Well 
known economic indicators include the seasonally- 
adjusted unemployment percentage and number of 
housing starts, both of which indicate overall economic 
condition. In these indicators, seasonal adjustment is 
made with a model, and most economists look at sev¬ 
eral indicators together instead of just one at a time. 
Similarly, landscape indicators can be measurements of 
ecosystem components (such as the amount of forest) 
or processes (such as net primary productivity), and 
models can be used to help interpret the measurements 
in order to understand overall ecological conditions. 



Figure 1.2 

This figure may help to understand how 
a city (bottom center) fits into a larger 
context of either watersheds (left 
branch) or parishes (right branch). 

















An Ecological Assessment of the Louisiana Tensas River Basin Chapter 1 



Figure 1.3 shows an example of measuring spatial pat¬ 
terns as an indicator of stream conditions. The distribution 
of streamside land cover has been mapped for the same 
subwatershed that is shown in Figure 1.2. Stream seg¬ 
ments that are green have adjacent forest; orange indi¬ 
cates that streams are next to agriculture or urban land 
covers. The pattern of streams in relation to land cover is 
an indicator of conditions within the stream. Forests often 
filter pollutants, preventing them from reaching the water, 


whereas agricultural and urban landuse often contribute 
pollutants to streams. They also dissipate energy associ¬ 
ated with major precipitation events; this reduces nutrient 
loading and the severity of flooding. A simple summary 
indicator might be the percentage of stream length in the 
parish that is adjacent to forest land cover. To refine this 
indicator, a model might help to account for “natural” 
conditions, for example whether or not forest was the 
natural land cover for the parish. 


Figure 1.3 


Spatial patterns of land cover in 
relation to streams for a 
subwatershed in the Tensas River 
region. Stream segments are colored 
green or orange, depending on 
whether the segments are adjacent to 
forest or agriculture/ urban land cover. 


































How Were the Landscape Indicators Selected? 


The starting point for selecting indicators was what 
people in the area said they cared about. These concerns 
were then matched to our ability to make meaningful 
measurements, recognizing that some things just can’t be 
measured very well given the available data or models. 
As a result of workshops and advice from people who live 
in the Tensas River Basin, three general environmental 
themes were identified-human use, forest and water. 
These three themes and the indicators measured within 
each theme are discussed in detail in Chapter 3. 

Figure 1.4 shows an example of a landscape indicator. In 
this example you can see that if forest patches are not 
connected, the forest is more vulnerable to the distur¬ 
bance. Figures 1.5 and 1.6 are pictorial representations of 
key landscape attributes that affect the sustainability of 
environmental condition across broad scales. 


Figure 1.5 shows some key landscape components that 
sustain a high quality environment, and Figure 1.6 shows 
some human modifications of the landscape that can 
reduce the sustainability of natural resources. These 
figures, although not of the Tensas River Basin, illustrate 
some of the important landscape indicators analyzed in 
this atlas. 

Landscapes are very complicated, and the generality of 
the conceptual models is an accurate reflection of the 
level of scientific understanding of landscape dynamics. 
Scientists who study landscape ecology are trying to 
improve our ability to interpret landscape indicators 
relative to environmental values. The improvements will 
help to interpret the information that is contained in this 
atlas, and will also suggest new landscape indicators or 
new ways to measure the ones that are included here. 

In the meantime, it is worth exploring how much is known 
about regional conditions, and what can be said by using 
state-of-the-art landscape indicators. 



4 


9 




Populatior 

persists 


Large-scale 

disturbance 


Recovery 


Large-scale 

disturbance 



Populatioi 
does not 
persist 


Time 


Figure 1.4 

Forest fragmentation can result in the loss of a species due to natural distur¬ 
bance. In this example larger, more connected forest sustains the species over 
time, whereas smaller, more isolated habitat loses the species over time. 

(In this example, tan is non-forest, red is occupied forest, and white is unoccu¬ 
pied forest.) 












































An Ecological Assessment of the Louisiana Tensas River Basin Chapter 1 


EH 







MlMg 


Figure 1.5 

A pictorial representation of some 
landscape components that sustain 
a high-quality environment. 












Riparian zones 
filter sediments 
and pollutants, 
especially in 
agricultural 
areas, in 
addition to 
providing 
important 
wildlife habitats 


O 


V 


Large blocks of 
interior forest 
habitat are 
important for 
many forest 
species 


The number of 
forest scales 
surrounding a 
point in the 
landscape 
determines the 
variety of 
forest species 
found there 


Forest edge 
habitat is 
important for 
many species 
that require more 
than one habitat 
type to survive 


MW 


Wm 


■ - 




Forest connectivity 
is crucial for the 
persistence of 
forest species, 
especially in areas 
with moderate 
amounts of 
agriculture 













































mmsm 








The amount and 
location of agriculture 
in a watershed 
influences 
landscape pattern 


Dams alter the natural 
habitats and hydrology 
of streams 


Agriculture areas near 
streams increase stream 
sediment loads and 
chemical inputs 


Figure 1.6 

A pictorial representation of some human 
modifications of the landscape that reduce the 
sustainability of natural resources 




2 \ 




Agriculture on steep 
slopes increases soil 
loss and sediment 
loading to streams 

























































An Ecological Assessment of the Louisiana Tensas River Basin Chapter 1 




Humans reduce riparian 
cover along streams, 
which decreases 
filtering capacity 



Forest harvest 
practices influence 
forest connectivity 
and patch sizes 




Air pollution spreads 
across the landscape, 
affecting regional 
air quality 








Roads near streams 
increase sediment and 
pollution loads by 
increasing surface 
runoff 



Population growth 
results in loss of forest 
and changes in overall 
watershed landscape 
pattern 















































How Were the Landscape Indicators Measured? 


Many kinds of data were used to prepare the indicators 
shown in this atlas. Federal agencies were the primary 
source for data, including maps of elevation, watershed 
boundaries, road and river locations, population, soils, 
and land cover. Sources included the U.S. Geological 
Survey (USGS), the U.S. Environmental Protection 
Agency (EPA), the U.S. Department of Agriculture 
(USDA), the U.S. Census Bureau, the U.S. Fish and 
Wildlife Service, the Louisiana Department of Environ¬ 
mental Quality, The Mississippi Alluvial Plain Project of 
The Nature Conservancy, and the North American 
Landscape Characterization (NALC) Program. 

Data collected by satellites were used to map land 
cover and its change over time. The sensors carried 
on satellites measure the light reflected from the 
Earth’s surface. Because different surfaces reflect 
different amounts of light at various wavelengths, it is 
possible to identify land cover from satellite measure¬ 
ments of reflected light. Figure 1.7 illustrates the 
differential reflectance properties of water, sediments 


suspended in water, and land surfaces for a typical satel¬ 
lite image. Examples of land cover maps derived from 
satellite images appear later in this atlas. 

In a typical digital map, data are stored as a series of 
numbers for each theme. These maps can be thought of 
as checkerboards, where each grid square (or pixel, which 
is an abbreviation of “picture element”) represents a data 
value for a particular landscape attribute (for example soils, 
topography, or land cover type) at a specific location. 


Figure 1.7 

Illustration of differential light 
reflectance properties for 
water, sediments suspended 
in water, and land surfaces 
over a portion of Vancouver, 
British Columbia -These 
images can be manipulated in 
various ways to extract 
information about the Earth’s 
surface. 

Source: North American 
Landscape 
Characterization 
Program 






















An Ecological Assessment of the Louisiana Tensas River Basin Chapter 1 


El 


i— 


Figure 1.8 illustrates one method of measuring a land¬ 
scape indicator. This method ("overlaying") simply 
overlays maps of different themes in order to extract 
information about spatial relationships among the 
themes. These relationships are then stored as a new 
map which combines the information from the original set 
of maps. 


Figure 1.8 

Land cover (with agriculture in red) is combined with topography to indicate 
agriculture on steep slopes. The combined map shows agriculture on slopes 
greater than 3%. 












































An Ecological Assessment of the Louisiana Tensas River Basin Chapter 1 


12 




How Were the Landscape Indicators 
Summarized? 


Usually, a watershed is defined as a catchment area 
that is drained by a single stream or river (i.e., the 
Mississippi watershed consists of all the area drained by 
the Mississippi river system, including all tributaries). 

The dividing lines between watersheds are formed by 
ridges. Water on one side flows into one stream, water 
on the other side flows into a different steam. Thus, 
watersheds are a natural unit defined by the landscape. 
Watersheds can be defined at several different scales. 
The USGS has divided the contiguous U.S. into 2,099 
watershed units known as 8-digit hydrologic accounting 
units (HUCs). The Tensas River Basin is defined as one 
of these 8-digit HUCs and serves as the boundary of our 
study area. 

The Tensas River Basin 8-digit HUC was further divided 
into 11-digit HUCs or subwatersheds (defined by the 
USDA) as a basis for analyzing and summarizing the 
landscape data (Figure 1.9). In many ecological studies, 
especially those which assess water-related concerns, 
subwatersheds are an appropriate unit for summarizing 
data. 


Fig 1.9 

Tensas River Basin divided into subwatersheds. 
Each subwatershed was given a unique number 
(2-9) for this report. 


The next chapter will look at the landscape from a na¬ 
tional perspective. As you read about the national land¬ 
scape, see how the Tensas River Basin compares to 
other watersheds in the United States. 



Subwatershed Hectares 

2 5625 

3 45532 

4 92534 

5 62012 

6 11136 

7 7353 

8 79748 

9 72365 


Total 


372000 (Hectares) 
930000 (Acres) 


i 














Chapter 2: The National Context 


I Before looking in detail at the Tensas River Basin, it is 
helpful to place the Basin within a national perspective. 

This chapter paints a picture of the lower 48 United States, 
showing differences and patterns among watersheds at a 
continental scale. A national context helps us interpret the 
overall condition of the Tensas River Basin, relative to the 
rest of the country. It also helps to determine if conditions 
like those found in the Tensas River Basin are likely to 
exist elsewhere. 

While it would be desirable to look in great detail over the 
entire nation, in practice only a few aspects of environmen¬ 
tal condition can be described in a consistent fashion 
nationwide. The coarse-scale maps in this chapter show 
watershed rankings based on a variety of landscape 
indicators. The rankings portray relative conditions across 
the nation but do not show the absolute values of indicators 
for each watershed. Indicator values are summarized in 
the companion bar charts. 

Data Sources 

Four main data sources were used here. The most 
important was a national map of land cover (Figure 2.1) 


which describes the types of vegetation covering an area, 
whether it is forest, crops or pasture, or covered with water 
or urban areas. Although the resolution (spatial and land 
cover) is fairly coarse (1 square kilometer and 9 of the 
original 160 land cover classes), the familiar national 
pattern is apparent-forests in the East, grasslands and 
crops in the Midwest, and shrublands, deserts, and moun¬ 
tain forests in the West. The Tensas River Basin is typical 
of the alluvial valley of the lower Mississippi River, riverside 
urban areas, agricultural valleys and plains, and forested 
wetlands. The variety of the land cover types in the Tensas 
River Basin, relative to other regions in the United States, 
can make spatial pattern an important ingredient for 
making environmental decisions in this region. 

Some additional information was used to calculate the 
indicators of environmental quality nationwide. Figure 2.2 
shows the maps of roads, streams, and watersheds. 
Clearly, not all the roads and streams are included. These 
maps may be appropriate for a nationwide overview, but 
much more detailed maps are needed for regional assess¬ 
ments such as the Tensas River Basin analysis described 
later. The watershed boundaries (Figure 2.2) identify 2,099 
individual watershed units across the United States. 



figure 2.1 


National land cover map. The U.S. Geological 
Survey produced this map of “Seasonal Land Cover 
Regions of the Conterminous United States. ’’ The map was 
derived from March-October (1990) 1-km Advanced Very High 
Resolution Radiometer (AVHRR) imagery, digital elevation, 
ecoregions, and climate data. The original 160 classes of land cover 
have been grouped into the 9 broad categories shown here. 


Western Forest 

Eastern Forest 

Croplands 

Shrublands 

Grasslands 

Wetlands 

Water 

Barren 

Urban 






































An Ecological Assessment of the Louisiana Tensas River Basin: Chapter 2 


For each watershed, the nine indicators (Table 2.1) included 
in this chapter were calculated from land cover and from the 
spatial relationships among roads, streams, and land cover. 


Figure 2.2 

National maps of (a) roads, (b) rivers, 
and (c) watershed boundaries. The 
maps are from the ArcLISA distribu¬ 
tion of the U.S. Geological Survey 
Digital Line Graph maps of rivers 
(1973) and roads (1980), and the 
U.S. Geological Survey map of 8- 
digit hydrologic accounting units. 



Table 2.1 List of landscape indicators used for the national context. 

U-Index (proportion of watershed area with anthropogenic land cover) 

Agriculture Index (proportion of watershed area with agriculture land cover) 

Number of natural land cover types per unit area 

Proportion of watershed that has forest land cover 

Average forest patch size as a percentage of watershed area 

Index of forest connectivity 

Proportion of total stream length with forest land cover 
Proportion of total stream length with anthropogenic land cover 
Number of roads crossing streams per unit stream length 















































An Ecological Assessment of the Louisiana Tensas River Basin Chapter 2 









— 




























































m 


An Ecological Assessment of the Louisiana Tensas River Basin: Chapter 2 






How to Read the Maps and Charts in this Report 

Figure 2.3 illustrates the types of maps and charts that 
appear in Chapter 2. 


The map of mid-Atlantic watersheds is color-coded 
to show relative conditions among watersheds. The 
colors range from red to green, indicating relatively 
“less desirable” and “more desirable” conditions, 
respectively. 


A quintile 
contains 1/5 of 
the watersheds. 
Quintiles are 
formed after 
ranking 

watersheds for 
the indicator. 


The Data Range 
shows the 
indicator values 
for watersheds 
contained in each 
quintile. 


Quintile 

1 

2 

3 

4 

5 


Data Range (Percent) 
<70.600 
70.600- 76.869 
76.870- 84.579 
84.580- 89.889 
>89.890 



The value shown on the X axis is the upper limit of a data 
range. For example, this bar shows the number of 
watersheds with data values between 60-70. 


A brief explanation of the essential methods is given. 



40 50 60 70 

Indicator Value 


Woody landcover along streams was calculated as the percent 
of streamlength with forest landcover types. By intersecting a 
buffer zone around each stream with the landcover, a data set is 
created which records all landcover types within a specified 
distance to stream center. 

Sources: USGS 1:100,000 River Reach 3 stream data, and 
MRLC 30 meter Landsat land-cover data. 


Figure 2.3 

How to read the maps and charts in this report. 





















































Ad Ecological Assessment of the Louisiana Tensas River Basin Chapter 2 



Human Use Patterns 

One of the simplest and most informative indicators of 
environmental impact is the extent to which humans 
have changed the natural vegetation to crops or urban 
land cover. These indicators are easy to interpret be¬ 
cause profound land cover changes influence almost 
every aspect of the environment from wildlife habitat to 
soil erosion. 

The national maps of human use intensity (Figure 2.4) 
show watershed rankings for both total human use- 
agriculture plus urban (Figure 2.4a) and only agriculture 
(Figure 2.4b). Urban areas are relatively minor in terms of 


total area, and farming areas are more extensive, so the 
two maps are very similar. Most of the human appropria¬ 
tion of land has occurred in the central United States and 
along the eastern seaboard. Higher elevations and the dry 
southwest appear to have been less impacted by conver¬ 
sion to agricultural or urban land cover. Like most of the 
south, Louisiana has a complicated pattern of land use that 
deserves more detailed attention. 

The chart gives some details about the distribution of 
human use intensity among watersheds. You can see that 
about 40% (800) of the watersheds have had only minor 


Agriculture or Urban Land Cover 


1000 . 
■o-d 800. 

|l 600 ' 

E jg 400. 
z| 200. 



10 2030405060708090 100 

Indicator V&lue 


Figure 2.4 

Proportion of watershed area with: (a) agriculture or urban land cover, (b) 
agriculture land cover. 


























An Ecological Assessment of the Louisiana Tensas River Basin: Chapter 2 


18 



i 



conversions to agriculture. These watersheds are prima¬ 
rily located in arid and mountainous areas, where grazing, 
although an important agricultural activity, does not change 
the grassland cover type at this scale. About 10% (200) of 
the Nation's watersheds have been almost completely 
converted to agricultural land; these are located mostly in 
the fertile central United States. 

The Tensas River Basin (Figure 2.4b) is shown in red 
putting it in the 5th quintile and giving it a data range of 
greater than 69. This means that there is a very high 
agricultural land use practice in this watershed. 


The complicated spatial patterns in the southern United 
States are evident in the map of land cover diversity 
(Figure 2.5). The map shows the watershed ranking for 
the number of different natural land cover types (anything 
except urban and agriculture) per unit area. These 
rankings are based on the original 160-class version of 
land cover and not the 9-class version shown in Figure 2.1. 

The greatest diversity of natural land cover is found in 
the western United States, where large changes in 
elevation produce different vegetation types at the top 
and bottom of the same watershed. But there are also 
diverse watersheds in coastal areas, including parts of 
the Mississippi Gulf region. 



i 


Indicator Value 
































An Ecological Assessment of the Louisiana Tensas River Basin Chapter 2 



Forest Patterns 

Forest patterns are particularly relevant in the southern 
United States because forests are the dominant natural 
vegetation cover. In contrast, natural land cover in the 
western United States also includes grasslands and 
shrublands, so forest patterns alone do not describe 
departures from potential natural vegetation types. We 
used three different indices of forest pattern in the water¬ 
sheds: amount of forest, average forest patch size, and 
forest connectivity. The resulting national rankings of 
watersheds for these forest indices are shown in Fiaure 
2 . 6 . 

The first map (Figure 2.6a) shows the watershed rankings 
of forest area, expressed as the percentage of total water¬ 


shed area. The chart indicates that about 20% (400) of the 
nation’s watersheds are almost completely forested, and 
that about 30% have little forest cover. About 100 water¬ 
sheds have no forests at all when measured at this scale. 
Forest cover is the most common vegetation type in nearly 
all of the watersheds east of the Ohio River. Many western 
watersheds are only forested at higher elevations. 

The two other maps are different ways of looking at 
whether the forests that do occur in a watershed are 
continuous or fragmented into smaller patches. Figure 
2.6b shows watershed rankings of average forest patch 
area or size, expressed as a percentage of total water¬ 
shed area. Figure 2.6c shows watershed rankings of 
forest connectivity, defined as the probability that a ran¬ 
domly selected forested spot on the map is adjacent to 
another forested spot. 


o T3 

t_ 0) 

0 -C 
-O £ 

E a) 

H 



National Rank 
Quintile Data Range 


< 0.19 
0.19-0.28 
0.29-0.42 
0.43-0.76 
> 0.77 


Indicator Value 


Natural Land 


Figure 2.5 

Number of natural land-cover types per 100 square kilometers of 
watershed area. 



























An Ecological Assessment of the Louisiana Tensas River Basin: Chapter 2 





/ 


All three maps have a similar pattern. Forest cover is 
usually continuous where most of the watershed is for¬ 
ested. In other cases, such as some watersheds in the 
southwest, forest cover is a minor component overall, and 
yet is still continuous where it does occur. Compared to 
potential natural cover conditions, forest loss and fragmen¬ 
tation of the remainder is significant in the northeast United 
States, along the east coast, and in the Mississippi River 
valley. The patterns in Louisiana are typical of those found 
in other places in the southern part of the country. 


Although the three maps have a similar pattern, the charts 
illustrate different views obtained by using different indica¬ 
tors. The distribution of watersheds is more or less 
uniform for the indicator based on percentage of forested 
area. The charts for the other two indicators suggest that 
in most watersheds, the average forest patch is a small 
percentage of total area, but that forest cover tends to be 
connected in whatever amount actually exists. 


Percentage of Watershed that is Forested 




O -C 
-Q c 

E« 400 

= ro 

200 


National Rank 
Quintile Data Range 

1 H < 2.0 

■ “ 2.0 - 22.0 

[ 22.0 - 60.0 

| 60.0 - 89.0 

■ >89.0 


10 20 30 40 50 60 70 80 90 100 

Indicator Value 


Figure 2.6 

Three forest pattern indicators: (a) percentage of watershed that is forested, (b) average forest patch size as a 
percentage of total watershed area, and (c) index of forest connectivity. 





























National Rank 
Quintile Data Range 

1 ■ < 0.1 

0.1 - 0.5 

0.5 - 1.9 

1.9 -11.6 

> 11.6 


Average Forest Patch Size 



National Rank 
Quintile Data Range 

1 ■ < 0.31 

2 ; J 0.31 -0.58 

3 □ 0.59 -0.78 

4 ■ 0.79 -0.92 

5 ■ > 0.92 


o ~o 
Z 0 

0 4 = 

E £ 
E 3 

if 


Indicator Value 











































Patterns Affecting Water Quality 

i 

Water quality and aquatic life are intimately related to land 
cover near streams. The vegetation near streams is 
referred to as riparian vegetation. It forms an important 
buffer zone protecting water quality. Natural vegetation 
absorbs agricultural nutrients, slows the rate of water 
movement, and is a settling zone for soil particles sus¬ 
pended in runoff. Riparian conditions are often evaluated 
within a few meters of a stream, but the larger landscape 
context is also important. 

One way to measure environmental conditions is to look at 
whether streams flow through predominantly forested or 
developed landscapes within a watershed. If there are no 
large urban areas or agricultural zones anywhere near 

<h 



streams, then it is less likely that water quality is being 
affected by these land uses. If forest cover dominates in 
the vicinity of streams, then there is greater opportunity 
for forests to buffer the conditions within streams. 

Watershed rankings of the proportions of stream length 
dominated by different land cover types are shown in 
Figure 2.7. These proportions are based on forest cover 
(Figure 2,7a) or urban and agriculture cover (Figure 2.7b) 
within about one-half kilometer of streams in each water¬ 
shed. Along the Mississippi River, the rankings for 
forested riparian zones show a sharp contrast between 
the area near the river and the forested areas to the east 
and west. The Tensas River Basin is one of the areas 
near the Mississippi River. 




(f> 

o "o 

i_ <i> 
0) 

J5 £ 
El 

3 ro 



Total Stream Length - Forested 


Tensas River Basin 


National Rank 
Quintile Data Range 


Indicator Ntelue 








Figure 2.7 

Proportion of total stream length that is: (a) forested, or 
(b) agriculture and urban. 







































An Ecological Assessment of the Louisiana Tensas River Basin Chapter 2 




The rankings based on the proportion of agriculture or 
urban land cover in riparian zones show similar patterns in 
the southern United States. The differences are more 
complicated in the western United States because 
nonforested vegetation may also be shrublands or grass¬ 
lands. 

Nationwide, the charts indicate that about 40% of the 
watersheds have riparian landscapes that are at least 70% 
forested, but an equal number of watersheds have very 
little forest cover in riparian landscapes. About 10% (200) 
of the watersheds have riparian landscapes that are nearly 
all agriculture or urban, and about the same number are 
almost completely undeveloped. 


Water quality is also related to larger patterns of land use 
over entire watersheds. For example, roads near streams 
affect water quality not only as direct pollution sources, but 
also because they represent paths for rapid runoff. The 
frequencies of roads crossing rivers were expressed here 
as the number of road crossings per unit river length in 
each watershed. This expression helps to adjust for 
differences in the total length of rivers between water¬ 
sheds. 

The map of watershed rankings for this indicator (Figure 
2.8) is complicated, and it does not closely resemble the 
national patterns found earlier when looking at land cover. 
The Tensas River Basin, like most of the Southeast and 
Midwest United States, has extensive road networks. Low 
lying areas are built-up to make roads thus changing the 
way water flows in the watershed. 


V) 

2E 
£ £ 
n 


890 

690 

400 

290 



Total Stream Length - Agriculture and Urban 


National Rank 
Quintile Data Range 

1 B < 3.4 


o 


10 2030405060708090 100 

Indicator Value 


Tensas River Basin 


15.7 -37.1 
37.1 -74.3 
>74.3 

































An Ecological Assessment of the 




/ 


National Context Summary 

Several important features of the Tensas River Basin can 
be identified by placing the region into a national context. 
The Tensas River Basin certainly has complicated 
spatial patterns of land cover, and the finer-scale analy¬ 
ses shown later in this Atlas seem warranted. In fact, the 
Tensas River Basin should be an excellent case study 
area because of the variety of conditions that it contains. 

Some patterns in the Tensas River Basin are typical of 
other areas along the southern agricultural belt. This 
means that what is learned in the Tensas may be appli¬ 
cable in other regions in the lower Mississippi Valley. 
Because the Tensas is also a transition zone between 
regions of more or less impact to the east and west, 
further studies here may also be relevant to environmen¬ 
tal monitoring in these other areas. 


The Tensas River is not the most highly impacted water¬ 
shed in the south, but it is different from the less im¬ 
pacted areas that are found at slightly higher elevations in 
the east and west. The patterns in the watershed 
creates an opportunity to consider a full range of environ¬ 
mental strategies from restoration of the more developed 
areas to protection aimed at forests and wetlands. This 
brief look at the Tensas River Basin in a national context 
has confirmed that many aspects of the broad-scale 
view of environmental quality can be usefully explored > 
here. 

r 

i 

) | 


2*8 
<l>-£ 
n £ 
E 3 

H 


Indicator Value 



Road - Stream Crossings 


National 


Quintile 


Tensas River Basin 




Figure 2.8 

Number of road-stream crossings per 100 kilometers of streams. 


































An Ecological Assessment of the Louisiana Tensas River Basin Chapter 3 




Chapter 3: The Tensas River Basin 
Landscape Assessment __ 


This chapter illustrates the landscape indicators used to 
assess watershed conditions in the Tensas River Basin. 
Each indicator is discussed separately; maps illustrate 
he relative rankings of subwatersheds and charts show 
; he distributions of indicator values. 

A/e begin with a brief look at the biophysical setting of 
^he Tensas River Basin including maps of the data used to 
’ ;alculate indicator values. Included are regional pictures 
)f topography, rivers, watershed boundaries, and land 
:over. An important criterion when choosing digital data 
was consistency across the watershed. Consistency is 
essential because the goal is a sub-watershed 
comparative assessment. 



Figure 3.1 

Shaded relief map of the Tensas River Basin. Source: U. S. Geological 
Survey, Digital Elevation Model, 3 arc-second. 


The landscape indicators are grouped according to three 
themes: human use, forests, and water. The following 
discussions introduce each theme and a number of 
analyses pertinent to the Tensas River Basin are applied 
to each theme. The interpretation of indicators are not 
exhaustive. In addition, these groups are subjective since 
any given indicator could be relevant to more than one 
theme and each affect water quality, the subject of Chapter 
4. For example, a discussion of an indicator of forest 
change along streams or riparian corridors appears in both 
the analysis of forest change and the analysis of water. 

The concluding section in this chapter describes a 
current program that focuses on restoring wetlands. 

Based on analyses presented in this chapter, a GIS 
illustration of areas of potential restoration gives land 
managers an example of a powerful decision tool. 

Biophysical Setting 

The Tensas River Basin encompasses approximately 
375,834 hectares (930,000 acres) of Mississippi River 
alluvial flood plain in Northeast Louisiana. The Tensas 
River is now hydrologically connected to the Atchafalaya 
River which is a major distributary of the Mississippi River. 
Historically, most of the Basin was covered with bottom¬ 
land hardwood forested wetlands. The bottomland 
hardwoods of the Tensas River Basin have been de¬ 
scribed as some of the richest ecosystems in the country 
in terms of diversity and productivity of plant and animal 
species. At the same time, these lands are recognized as 
some of the nation's most productive farmland for grain 
and fiber. The result is a conflict of land use between 
traditional row crop agricultural interests and concern for a 
healthy, diverse, and stable ecosystem. 

The alluvial flood plain of the region forms the backdrop 
for all of the physical and biological processes that shape 
the watershed. Generally when you look at a map of a 
watershed, whether it is a physical map, a vegetation 
map, or even a socio-political map, the most striking 
features of the landscape are created by topographic 
features. In the Tensas River Basin (Figure 3.1) a lack of 
topographic variety encourages a variety of different 
landforms including point-bars, abandoned river courses, 
abandoned channels, natural levees, and backswamps. 
The Tensas River Basin is unique in that natural levees 
along the riparian vegetation lie on the highest ground in 
the Basin. This causes drainage water to run parallel to 
streams for many miles before actually entering the 
stream and river water channels. Wetlands and 











An Ecological Assessment of the Louisiana Tensas River Basin Chapter 3 




r 





/ 


backswamps then become the vegetation filtering areas 
for pollutants and nutrients. These landforms create a 
diverse physical and ecological region. Bayous, channels, 
streams, and rivers direct the flow of water across the 
landscape and are dominant features in the Tensas River 
Basin (Figure 3.2). In the previous chapter we looked at 
the Tensas River Basin in the context of a watershed 
within the lower 48 contiguous states. In this chapter, we 
further divide the watershed into topographically relevant 
subwatersheds or zones and examine landscape indica¬ 


tors based on these subwatersheds. These 
subwatersheds, known as 11-digit hydrological accounting 
zones, were defined by combining the USGS 8-digit HUC 
boundary with the NRCS 11-digit boundaries and are 



shown in Figure 3.3. 


Figure 3.2 

1991/92 NALC Image 
60-meter False Color Composite 


Note that Zones 2, 7, and 9 were not defined as 11-digit 
hydrologic accounting units by NRCS but do fall within the 
boundary of the 8-digit USGS HUC boundary. 
Subwatersheds 2 and 7 may be parts of other 
subwatersheds or contain most likely, bayous in which 
water could flow in many directions. 

Therefore, these areas are included in the combined 11- 
digit boundary but may not actually be totally hydrologi- 
cally linked to the Basin. Subwatershed 9 appears to be 
linked to the Basin through a major tributary. The indica¬ 
tor values calculated for zones 2 and 7 are probably not 
as reliable as the values for those zones in which an 
entire subwatershed was in the assessment area. 


Combination of USGS 8-digit HUC boundaries with 

NRCS 11-digit boundaries. Zones 2,7, and 9 are shown in red. 



USGS 8-Digit 
Accounting Units 


NRCS 11-Digit 
Accounting Units 


Combined 8 and 11 Digit 
Accounting Unit Zones 


Figure 3.3 
















Land Cover 




I 



Land cover is the product of past land uses on the 
backdrop of the biophysical setting. A map of land 
cover is essentially a picture of the dominant vegeta¬ 
tive, water, and urban cover in an area. Figure 3.4 
illustrates the land cover of the Tensas River Basin. 

This land cover map was jointly prepared by the 
USFWS, the USGS Biological Research Division 
(formerly known as the National Biological Service) 
and the University of Arkansas at Fayetteville. They 
used Landsat Thematic Mapper 30-meter satellite 
imagery to derive the 17 classes displayed in the map. 
Although individual pixels are far too small to be 
rendered accurately here, the visual impression of 
broad-scale watershed patterns is readily apparent. 

This Land Cover map can be used for many types of 
landscape analyses and assessments. For our 
assessment of the land cover we started with only 
three classes: forest, human use, and water. Later on 
in this chapter we explain in much more detail 
how these were derived. 

The two most dominant land cover types in the 
Tensas River Basin are forest and human use, which 
presently cover about 22% and 77% of the area, 
respectively. Some of the subwatersheds are prima¬ 
rily forested and approach 60% forest cover. Some 
subwatersheds have less than 5% forest cover. 

Where forests have been removed, agriculture and 
urban land covers become more dominant. The 
median amount of urban land cover per watershed is 
about 2%. Agriculture is an extremely important land 
use in the region; four subwatersheds have more than 
60% of agriculture land cover. 


Landcover 

Cypress/Willow 
Wet Hardwoods 
Hardwoods 
Edge Forest 
Other Forest 
Scrub/Shrub 
Conservation Reserve 
Grass 
Lakes 
Urban 
Rice 
Soybean 
Cotton 
Milo 

Sugar Cane 
Com 

Other Crops 


Figure 3.4 

Land Cover in the Tensas River Basin. Source: USFWS, BRD, and the 
University of Arkansas at Fayetteville. Landsat TM 30 -meter satellite imagery, 





















An Ecological Assessment of the Louisiana Tensas River Basin Chapter 3 




Humans in the Landscape 


Human Use Index 


Humans structure the landscape for their purposes, and 
landscapes structure human activities. For example, 
humans may decide the shapes and sizes of individual 
agricultural fields, but watershed-scale patterns of topog¬ 
raphy, soils, and geology determine whether or not there 
can be fields at all. Because human-dominated land¬ 
scapes are used for different purposes which impose 
different patterns, land use history is always important for 
understanding local landscapes. The interplay between 
humans and landscapes has created a tapestry of multi¬ 
scale patterns in the Tensas River Basin, and combina¬ 
tions of these two factors influence the sustainability of 
ecological processes. 

Population Density and Change 


The proportion of an area that is used for agriculture or 
urban land use is a measure of human use known as the 
U-index. We often assume that humans tend to simplify 
their environment. At landscape scales, however, the map 
of human land use displays complicated patterns (Figure 
3.4, Land Cover). The scale at the transition from simple 
to complicated patterns might be a measure of the scale to 
which humans have structured a landscape or, conversely, 
the scale at which geophysical processes constrain 
human activity. By looking at watershed patterns of the U- 
index, it is possible to identify those areas which have 
experienced the greatest land cover conversion from the 
natural cover of vegetation. 


According to the U.S. Census Bureau, the population of 
the Tensas River Basin in 1990 was about 29,300 
people, which represents about 0.0001 of the total 
population of the United States. With a population of 
29,300 covering an area of 3,763 square kilometers, the 
average population density of the Tensas Basin is about 
7.8 people per square kilometer. 

Between 1970 and 1990, the total population in the 
Tensas Basin (East Carroll, Madison, and Tensas par¬ 
ishes) decreased from 37,680 to 29,300. Thus, the 
average population density decreased from about 10 
people per square kilometer to 7.8 people per square 
kilometer. Figure 3.5 shows the population of the 
Tensas River Basin by parishes and the populations of 
three cities in the Basin. 




Figure 3.5 

Population (1990) of Louisiana Parishes within the 
Tensas River Basin. 





















































An Ecological Assessment of the Louisiana Tensas River Basin Chapter 3 


The watershed pattern of human use in 1991/92 is re¬ 
flected in the subwatershed rankings over the region 
(Figure 3.6). The highest U-index value for a 
subwatershed is about 96.7%, which means that 96.7% of 
that watershed has agricultural or urban land cover. The 
lowest value is 38.9%, and the average value is 77.3%. 
Compared to the national human use maps in Chapter 2, 
this is a very high human use index. 



Roads 

Roads and other transportation corridors are designed to 
connect the human-dominated elements of a landscape. 
The network of roads in the Tensas River Basin permits 
access, commerce, and communication throughout the 
region. Roads are also important for connectivity among 
ecological communities. Sometimes roads restrict eco¬ 
logical communities, as in the case of animals that are 
unable to cross roads. Sometimes roads enhance 
ecological communities, such as for plant species that 
spread along disturbed roadsides. In some cases, areas 
remote from roads may better accommodate wildlife, e.g., 
Louisiana black bears. The influence of a given road 
extends for some distance, depending on such things as 
road size and surface type, traffic volume, and type of 
use. There are few places in the Tensas River Basin that 
are entirely free of their influence. 

According to the road maps used for this atlas, there are 
about 3,666 kilometers of roads in the Tensas River 
Basin. This data set (U.S. Census TIGER) includes all 
types of roads-interstates, U.S. and State highways, 
county roads, and city streets. This works out to an 
average of 125 meters of road per person in the region. 

It is no wonder that roads are one of the most important 
human features in the Tensas River Basin landscape 
today. 

Figure 3.7 illustrates the road network within the Tensas 
River Basin. It is immediately apparent, with the excep¬ 
tion of road concentration in the urban areas of Lake 
Providence, Tallulah, and Saint Joseph, that roads are 
uniformly distributed throughout the Basin. Figure 3.7 
also breaks out kilometers of roads by zone. 


Figure 3.6. 

Human Use (U) Index, Tensas River Basin. 



















An Ecological Assessment of the Louisiana Tensas River Basin Chapter 3 




Roads Along Streams 


Roads affect stream water in many ways and roads in 
close proximity to streams have the most potential for 
adverse effects on stream water quality. Figure 3.8 
shows road intersections with streams by sub-watershed 
in the Tensas River Basin. Since roads have an impervi¬ 
ous surface, and ditches are built to channel water off 
roads and into streams, the rate of water runoff is higher 
where there are more roads. Although large spills of 
polluting materials are rare and often quickly contained, 
small spills of petroleum products, antifreeze, and other 
vehicle-related chemicals happen every day on every 
mile of road in the region. These small spills eventually 
go somewhere, usually into streams. Road construction 
near streams is a temporary stress on water quality, but 
after construction, the roads remain, and routine mainte¬ 
nance can contribute to poorer water quality. For these 
and other reasons it is important to consider how the 
proximity of roads to streams might influence regional 
water quality. 

Forests in the Landscapes 

Forests are important elements of both natural and 
human-dominated landscapes. Forests provide many 
benefits including wood fiber, outdoor recreation, wildlife 
habitat, and regulation of some watershed hydrologic 
functions. Historic patterns of land use and development 
have created the present distribution of forests from what 
once was essentially all forest. There have also been 
changes in the plant and animal species which live in 
forested environments. In this section, the pattern of the 
existing forest cover is described as it affects various 
environmental values, particularly wildlife habitat. 


Percentage of Forest Cover 


Zone 

Kilometers 

Ha 

Ratio of Km/Ha 

2 

83.5 

5,601 

1.49 

3 

485.0 

45,387 

1.07 

4 

949.9 

92,471 

1.03 

5 

491.4 

61,742 

0.80 

6 

46.7 

11,126 

0.42 

7 

63.6 

7,345 

0.87 

8 

778.4 

79,713 

0.98 

9 

767.1 

72,212 

1.06 

Total 

3,666.0 

375,807 

0.98 (Avg) 


Figure 3.7 

Roads in the Tensas River Basin. Source: US Census TIGER. 


At one time, nearly all parts of the Tensas River Basin 
were forested. Today, the amount of remaining forests 
helps to indicate the probable condition of streams within 
each watershed. The proportion of watershed covered 
by forest is indicative, but not conclusive, of stream 
conditions because the specific types of non-forest land 
cover (such as urban or crop) are also important. 






















An Ecological Assessment of the Louisiana Tensas River Basin Chapter 3 


. 



31 




Figure 3.8 

Roads Crossing Streams. 








# of Crossings 

Ha 

Xings/Ha 

18 

5,601 

0.32 

159 

45,387 

0.35 

288 

92,471 

0.31 

116 

61,742 

0.19 

8 

11,126 

0.07 

20 

7,346 

0.27 

220 

79,713 

0.28 

238 

72,212 

0.33 

1067 

375,807 

0.28 


The forest cover map of the Tensas River Basin (Figure 

3.9) is based on the North America Landscape Charac¬ 
terization (NALC) satellite imagery data. NALC satellite 
data, available since the early 1970s, is a Federal effort to 
create similar data sets for the entire country. The resolu¬ 
tion of the NALC data is 60 meters; thus, each pixel 
(picture element) represents an area about the size of a 
football field. Compare the land cover map shown in 
Figure 3.4 (30-meter pixels) to the NALC data (Figure 

3.9) . 


Although individual pixels are far too small to be rendered 
accurately here, the visual impression of broad-scale 
regional patterns is readily apparent. Forest vegetation 
shows up on the NALC image as red in color, agriculture 
shows up as light red, grey, light blue and white. When the 
NALC Image is enlarged the agriculture almost always 
shows a pattern of rows or right angles typical of farm 
fields. 


















An Ecological Assessment of the Louisiana Tensas River Basin Chapter 3 






1972 NALC Image 
False Color 
Composite 


Figure 3.9a. 



1991/1992 
NALC Image 
False Color 
Composite 


Figure 3.9b. 




Figure 3.9d. 


1991/1992 NALC 
Image with Land 
Cover Classification 



Difference between 
the 1972 NALC 
Image and the 
1991/1992 NALC 
Image results in 
a Forest Loss 
and Gain Image 


Figure 3.9e. 


LEGEND 


I I Tensas Study Area 


Land Cover 
Forest 


Forest Loss 
Forest Gain 
Human Use 
I Water 


Figure 3.9 

Forest Cover in the Tensas River Basin. 























An Ecological Assessment of the Louisiana Tensas River Basin Chapter 3 


ED 


The NALC images (Figure 3.9a and 3.9b) were classi¬ 
fied to show landuse (Figures 3.9c and 3.9d). The 
classifications were forest, human use (urban and 
agriculture), and water. The 1972 image was compared 
to the 1991/92 image and changes in forest areas and 
human use areas were calculated. The forest cover 
changes are shown in Figure 3.9e. As the figure shows, 
there was significant forest loss during that time period. 
Subwatersheds, 4, 5, 8, and 9 have had substantial 
forested loss. The northern subwatershed, 2 and 3, have 
had little forest loss because they had been converted to 
agriculture long before 1970. Where forests have been 
removed over the last 20 years, agriculture land cover has 
become more dominant, as can be seen by comparing 
Figures 3.9c with 3.9d. 


Forest Fragmentation 

As in other regions of the United States, forest fragmen¬ 
tation is an important issue in the Tensas River Basin. 
Although the word has several meanings, the general 
concept is that what was once a large continuous forest 
has been broken up into smaller pieces. In the eastern 
United States, forest loss is generally associated with 
agriculture and urban uses which remove some forest 
and leave the remaining stands in smaller, isolated 
blocks. The pattern of forest loss can be important as the 
amount lost. For example, a checkerboard pattern 
exhibits more fragmentation than a clumped pattern of 
the same amount of forest. 


Forest fragmentation was assessed by using the forest 
and non-forest data classification shown in Figures 3.9c 
and 3.9d. The fragmentation statistic measures the 
probability that a randomly selected forested spot is 
adjacent to another forested spot. High values indicate 
low fragmentation. This statistic was calculated for 1972 
as 88% and 1991/92 as 84%. These are relatively high 
values which indicate that much of the forest area in the 
Tensas River Basin is interconnected. Forest fragmenta¬ 
tion will be discussed in more detail later in this chapter. 

Percent of the Watershed in the Largest Forest 
Patch 

About 30 years ago, A.W. Kuchler made maps of poten¬ 
tial natural vegetation, that is, the vegetation that would 
occur if vegetation was only influenced by natural pro¬ 
cesses such as weather and fire. In the Tensas River 
Basin, Kuchler’s maps show that the potential natural 
vegetation is almost exclusively forest. 

Previous discussion introduced the concepts of forest 
loss (Figure 3.9) and forest fragmentation. Consider a 
watershed with some given amount of forest cover. If the 
forest is in one continuous stand, then the largest forest 
stand equals the total forest cover. If the largest stand is 
smaller than this expected value, then fragmentation has 
occurred and the remaining forest cover is discontinuous. 

The largest forest patch in the Tensas River Basin in 1972 
was 54,939.2 hectares compared to the largest forest 
patch in 1991/92 of 37,997.3 hectares. This is a loss of 
16,941.9 hectares from the largest patch. The average 
forest patch in 1972 was 38.9 hectares and in 1991/92 
was 23.1 This is a loss in average forest patch size of 
15.8 hectares throughout the Tensas River Basin. 


These forest patch size statistics may be used to deter¬ 
mine where local reforestation would best improve forest 
connectivity regionally. A significant increase in the size 
of the largest forest patch could be made by joining the 
two largest patches. More information on Wetland Forest 
restoration is given later in this chapter. 






















An Ecological Assessment of the Louisiana Tensas River Basin Chapter 3 






Detailed Forest Analysis of the Tensas River 
Basin , 1970s to 1990s. 

The landscape analysis began with taking the 1972 
classified data and running computer programs which 
calculate the various landscape statistics. The landscape 
statistics for the 1972 and 1991/92 data are given in 
Tables 3.1 and 3.2 (all tables are found at the end of 
Chapter 3). Figures 3.10 and 3.11 show the classified 
images of the Tensas River Basin for 1972 and 1991/92 
respectively. The Tensas River Basin was classified into 
three categories: forest, human use (urban and agricul¬ 
ture), and water. The water statistics are not presented 
in the tables. 

In 1972 the data show the amount of forest area in the 
Tensas River Basin as 126,298 hectares and the human 
use as 244,522 hectares. These represent 33.6% and 
65.1 % of the total Tensas River Basin area. In 1991/92 the 
amount of forest area is 80,807 hectares and human use 
is 290,336 hectares. These represent 21.5% and 77.3% of 
the total Tensas River Basin. The net forest loss for this 
period is 45,491 hectares (112,463 acres) or 12.3% of the 
land area. These data indicate a substantial decrease in 
forest and an increase in human use over the years. The 
totals and percents are given for each subwatershed 
(Tables 3.1 and 3.2). The landscape analysis for percent 
forest change which includes the entire Tensas River 
Basin is shown in Table 3.3. The classified data which 
show the forest vegetation change is given in Figure 3.12. 
These data were also analyzed by subwatershed and 
presented in Table 3.3. 

Forest patch statistics are also given in Tables 3.1 and 
3.2. A high same-type forest edge percentage indicates 
low forest fragmentation. In 1991/92, subwatershed 
number 6 has a same-type edge percentage of 94.9. 

This is a very high value showing that the forest in 
subwatershed number 6 is highly connected. The Tensas 
River National Wildlife Refuge is located in subwatershed 
number 6 which accounts for the high value as connected 
forest patches are needed for wildlife management. The 
largest forest patch size and the average patch size are 
also given in these tables. 



z 


Land Cover 
Forest 
Human Use 
HBj Water 


Figure 3.10 

1970s Classified Image, Land Cover. 

































An Ecological Assessment of the Louisiana Tensas River Basin Chapter 3 








Land Cover 
Forest 
Forest Loss 
Forest Gain 
Human Use 
Water 


Land Cover 
Forest 
Human Use 
I Water 


Figure 3.11 

1990s Classified Image, Land Cover. 


Figure 3.12 

Classified Image, Vegetation Change 1970s to 1990s. 





















EH 


An Ecological Assessment of the Louisiana Tensas River Basin Chapter 3 




Vegetation Change 

In the previous sections, we discussed landscape 
change based on NALC images that had been classi¬ 
fied. Another method is to calculate indices directly 
from the satellite imagery. It is interesting to compare 
the results of the preceding landscape change analy¬ 
sis with those presented in the following discussion. 

A common perception is that patterns of forest and 
agriculture and urban areas remain constant over time. 

In this section we present patterns of vegetation 
change measured by comparing satellite images from 
1972 and a composite of 1991 and 1992. The change 
is determined by using a vegetation index called Nor¬ 
malized Difference Vegetation Index (NDVI) which was 
calculated for each pixel on each of the two dates. 

When the NDVI values are essentially the same at both 
dates, then there has been no change. When the 
value is greater in 1972 than 1991/92, we interpret this 
as vegetation loss. When the value in 1972 is less than 
1991/92, we interpret this as vegetation gain. Total 
vegetation change is taken to be the sum of loss and 
gain on an area basis. 

The NDVI can be derived from satellite images because 
the near infrared band produces a large reflectance 
compared to the visible red band when looking at vegeta¬ 
tion. The formula for NDVI is: 

NDVI = Infrared Band - Visible Red Band 
Infrared Band + Visible Red Band 

The NDVI also has the advantage of compensating for 
changing illumination conditions like surface slope, 
aspect, and other factors. Indexes derived by NDVI 
range from -1.0 to 1.0, where negative index values 
represent clouds, water, and snow. Index values near 
zero represent barren soil and rock, and positive index 
values are indicators of the variation in vegetation. 

Comparison of temporal changes in reflectance mea¬ 
sures from satellites, such as NDVI, can be useful for 
gaining insight into land cover changes when land cover 
maps from two different dates are not available. Inter¬ 
preting the measurements relative to land cover change 
is not straightforward though because some changes in 
reflectance are not changes in land cover. Crop rotation 
is a good example. Change in NDVI measurements 
may be the result of seeing a field in production on one 


date and fallow on the other. Interpretation of these 
measurements for actual land cover change requires a 
lot of additional work beyond calculating their difference 
over time. 

Despite the complications, the amount and spatial pat¬ 
tern of NDVI change is important. For example, many of 
the decreases in NDVI turn out to be associated with 
road improvements, new residential developments, 
urbanization projects, and construction of reservoirs. 

Gains in NDVI may be the result of crop rotation or matur¬ 
ing vegetation in residential developments. Gains in NDVI 
appear to be associated with both natural and anthropo¬ 
genic processes, whereas non-crop rotation NDVI losses 
appear to be more consistently associated with anthropo¬ 
genic activities. 

These examples show that, after calibration, NDVI 
changes over time can help answer several ecologically 
important questions such as: (1) how much change has 
occurred? (2) is vegetation change evenly distributed 
over all the watersheds in the region, and (3) is vegeta¬ 
tion change concentrated in the headwater regions of 
streams? Figure 3.13 shows the vegetation change from 
1972 through 1991/92. 



Tensas River Basin Agriculture Field. 



































An Ecological Assessment of the Louisiana Tensas River Basin Chapter 3 



Vegetation Change by Subwatershed 



Figure 3.14 shows the percentage of total NDVI change 
for all subwatersheds in the Tensas River Basin. All of 
the changes observed represent losses in vegetation. 
Vegetation loss shows a general pattern with the highest 
rate of change in subwatershed 8. Vegetation changes in 
subwatersheds 2, 3, and 4 are most likely due to farming 
practices of rotating crops. Lower vegetation changes 
can be noted in subwatersheds 6 and 7 due to the 
relative stability of the forests in those areas. The high 
loss in vegetation in subwatershed 8 is most likely due to 
forest loss in that area since 1972. Table 3.4 contains 
the numerical data of gains and loss by pixels and the 
percentage for each subwatershed. Similar patterns of 
vegetation changes were observed in Figure 3.9 which 
showed forest losses and gains based on classified 
NALC images. 



Tensas River Basin, Bottomland Hardwoods. 


Figure 3.13 

NDVI Change between 1972 and 1991/92 in the Tensas River Basin. 
Red = Loss and Green = Gain. 



















An Ecological Assessment of the Louisiana Tensas River Basin Chapter 3 


38 




1 

_ 


i 


Forest and Crop Land Along Streams 



Figure 3.14 

Net percentage of change in the NDVI for the Tensas River Basin from 1972 
to 1991/92 by subwatershed. All changes represent net losses. 


The strip of vegetation along streams is known as the 
riparian vegetation zone. It is commonly described by the 
types of vegetation it contains. In an ideal situation, many 
pollutants and fertilizers will be intercepted or absorbed by 
the riparian vegetation, and this process helps to keep the 
streams clean. Bank erosion is also mitigated by intact 
riparian vegetation. The Tensas River Basin is unique in 
the natural levees along with the riparian vegetation lie on 
the highest ground in the Basin. This causes drainage 
water to run parallel to streams for many miles before 
actually entering the streams and river water channels. 
Wetlands and backswamps then become the vegetation 
filtering areas for pollutants and nutrients. 

Forested riparian zones are a natural part of the healthiest 
stream ecosystems in the southern United States. They 
provide an effective barrier to runoff of water, pollutants, 
and excess fertilizer and support a variety of valuable plant 
and wildlife species. Conversely, when riparian forests 
are replace by agriculture, the riparian zone not only loses 
its natural buffering capacity but now becomes a potential 
source of pollution and excess fertilizer. Agricultural 
practices usually employ fertilizers, pesticides, and other 
chemicals that are essential to crop growth and yield. 
These chemicals can more readily be moved into 
streams which flow through agricultural fields, in compari¬ 
son to streams which flow through forests. The maps on 
these pages illustrate differences among watersheds in 
the length of stream that has either forest or crop cover in 
the riparian zone. 

Figure 3.15 shows the relative amount of forests and 
human use land cover within a 360-meter buffer riparian 
zone along the Tensas River and its major tributaries. 
Figure 3.16 shows the amount of forests and human use 
land cover within a 120-meter buffer zone on either side of 
all the stream reaches of the Tensas River Basin. 
Subwatersheds 2 and 3 have the least percentage of 
forest in riparian zones. Subwatersheds to the south have 
the greatest amount of forested riparian cover. All of the 
sub-watersheds have stream length with some cropland 
cover. The watersheds with the highest potential for 
negative impacts are in subwatersheds 2, 3, and 4. 

Whereas the distribution of riparian forests is an indica¬ 
tor of natural buffering capacity, the distribution of crop 
land cover in riparian zones is an indicator of potential 
problems. Figure 3.17 zooms in on stream length 
between subwatersheds 5 and 8 and shows cropland 
cover (human use) and forested areas in the riparian 
zone. All of the areas shown in red were historically 
forested and are now cropland cover. 



















An Ecological Assessment of the Louisiana Tensas River Basin Chapter 3 





Figure 3.1 
Next Page 


Forest 91/92 
Forest Loss 
Forest Gain 
Human Use 
Water 



Forest 91/92 
Forest Loss 
Forest Gain 
Human Use 
Water 


Figure 3.15 F/gure 3.16 

Riparian Zone of Tensas River and its Major Tributaries (360-meter buffer). Riparian Zone of a „ stream Reaches (12 0-meter buffer) 






























An Ecological Assessment of the Louisiana Tensas River Basin Chapter 3 



Water and the Landscape 




Forest 
Forest Loss 
Forest Gain 
Human Use 
Water 


Everyone knows the importance of water. But many 
people do not realize how much its quality depends on 
the surrounding landscape. Water quality, like landscape 
condition, is the cumulative impact of environmental 
stress and land management practices at broad scales. 
Changes in the distribution and pattern of ecological 
resources and human activities can alter fundamental 
water processes including flow and balance, nutrient and 
sediment loading, and chemistry. These changes can, in 
turn, influence the water quality and quantity that are 
valued by society. Figures 3.16 and 3.18 illustrate the 
stream network within the Tensas River Basin. 

This section presents landscape indicators that are 
related to water quality in the streams of the Tensas 
River Basin. “Riparian” indicators describe landscape 
conditions near streams and “watershed” indicators 
describe conditions over entire watersheds. The riparian 
indicators include measures of human activities (agricul¬ 
ture and roads) near streams and the amount of wetland 
area. The size and amount of riparian buffers along 
streambanks is an important determinant of soil loss and 
sediment movement, which in turn affect water quality. 

The group of watershed indicators presented here 
primarily measure the potential for soil and nutrient 
losses from surrounding landscapes which would ulti¬ 
mately be deposited in streams. Put simply, watersheds 
covered by natural forests are more likely to be in good 
condition than watersheds with high percentages of 
intensive human land uses. Because intact riparian 
areas buffer streams from the potentially adverse effects 
of watershed-scale events like erosion, both types of 
indicators need to be evaluated when considering overall 
landscape influences on stream condition and water 
quality. 


Figure 3.17 

Enlargement of Riparian Zone with 1992 NALC Image. 





















An Ecological Assessment of the Louisiana Tensas River Basin Chapter 3 



Watershed Indicators 








While streamside conditions are important, it is also 
important to have indicators of potential impacts on water 
quality from sources throughout the watershed. It was 
mentioned earlier that the watershed indicators pre¬ 
sented here are primarily concerned with soil erosion and 
runoff processes. These indicators are relatively easy to 
determine from existing databases. In any case, erosion 
processes are extremely important. The results of in¬ 
creased erosion may include reduced agricultural produc¬ 
tivity, increased water treatment costs, introduction of 
pesticides and fertilizers in the water supply, loss of 
habitat for fish and other species, and reduced recreation 
potential. 


In years past the freshwater marshes, stream bank 
areas, and bottomland swamps of the Tensas River 
Basin were under strong development pressures. Large 
portions of forest near streams and in backwater swamp 
areas were converted to agriculture. This loss of for¬ 
ested areas interfered with the soil and water interactions 
in forested wetlands that removes pollution (excess 
nutrients) before it enters streams, lakes, and estuaries. 
Wetland forests also dissipate peak flows during floods 
and release the waters slowly, reducing damage to down¬ 
stream farms and cities. Preserving or restoring wetland 
forests has other economic benefits including wetland- 
based recreation such as hunting and harvesting wetland 
plants. Residents of the Tensas River Basin realize that 
the vegetation along a stream and in backswamp areas 
can influence the condition of both the stream bank and 
the water in the stream. They began restoration efforts in 
the early 1990s. 


Figure 3.18 


Stream network in the Tensas River Basin. Source: EPA RF3. 













m 


An Ecological Assessment of the Louisiana Tensas River Basin Chapter 3 



Riparian Analysis 

The conditions of the riparian ecosystem over a whole 
watershed can be studied in order to learn where, for 
example, a restoration project would most improve water 
quality. Similarly, a characterization of riparian conditions 
over the entire Tensas River Basin can help to identify 
which areas of the Basin are most likely to see improved 
water quality as a result of riparian vegetation improve¬ 
ments. 


The forest change data for the riparian areas of the Tensas 
River Basin are given in Table 3.6. This analysis was done 
by taking the forest change data and applying it to all the 
streams in the watershed in areas 120 meters on either 
side of the stream. This is shown in Figure 3.11. Each 
subwatershed was also analyzed so a comparison can be 
made between the different subwatersheds. 



Forest Loss and Gain 
within 360 meters of 
Tensas River and 
Major Tributaries 


1972 NALC Image 
with Forest Change 


NALC Image with 
360 meter Buffer 


Cover 
Forest 
Forest Loss 
Forest Gain 
Human Use 
Water 


Figure 3.19 

Vegetation Change within 360 meters of Tensas River and Major Tributaries. 



























An Ecological Assessment of the Louisiana Tensas River Basin Chapter 3 




This comparison can be seen in Table 3.6. Riparian areas 
have undergone changes in the Basin. In most cases, the 
forest change tends to be higher near streams. The 
highest forest change in the riparian areas was in 
subwatershed 8 where there was a 23.7 percent loss in 
forest vegetation. This data shows us where land use 
practices can be changed to help improve water quality. 
Improvements could be made in subwatershed 8 if the 
land owners are willing to convert the riparian strip of land 
back to forest vegetation. 

Vegetation Change along the Tensas River Reach 


Backswamp Area Analysis 

The backswamp areas of the Tensas River Basin play a 
very important role in the ecology of this water system. 

The land is very flat which means that water can move into 
stream channels and it can also collect in low-lying areas. 
These areas, which can hold water for months at a time 
after big rain events, make up lakes, swamps, and wetland 
forests. Figure 3.20 shows the location of Tensas River 
Basin backswamp areas. Information about changes to 
and locations of the backswamp areas will be an indicator 
of water quality in this watershed. 


The vegetation along a stream affects the condition of 
the stream and the water in the stream. This analysis 
includes the area 360 meters on either side of the main 
channel of the Tensas River and the same distance on 
either side of the major tributaries of the Tensas River. 
The results are shown in Table 3.5 and illustrated in 
Figure 3.19. 

Compared to the overall Tensas River Basin which had a 
21.3% overall loss in forest vegetation the data show that 
loss in the immediate area of the river and its tributaries 
was only 7.5%. Although the loss of forest vegetation 
was 7.5%, it shows that more vegetation was left within 
360-meters of the main portion of the Tensas River and 
should help prevent stream bank erosion and excess 
nutrient loading to the river. 


The backswamp areas in the Tensas River Basin are 
very important in terms of using the excess nutrients 
found in the water and holding water during heavy rain 
events. The combination of these flood areas with the 
forest change landscape indicators is shown in Table 3.7 
and Figure 3.21. Forest change in backswamp areas is 
somewhat different that in other areas. A higher per¬ 
centage of backswamp area was lost in subwatershed 4 
(around the town of Tallulah) than in the entire Tensas 
watershed. A complete comparison between the Tensas 
subwatersheds is given in Table 3.7. 


























An Ecological Assessment of the Louisiana Tensas River Basin Chapter 3 







LMUl Backswamp Areas 


Land cover 
Forest 
Forest Loss 
Human Use 
Forest Gain 
Water 


Figure 3.20. Figure 3.21 

Backswamps in the Tensas River Basin. F ° rest Chan ° e in Backswamp Areas. 


Source: The Nature Conservancy and the 
Biological Resources Division of the USGS 























An Ecological Assessment of the Louisiana Tensas River Basin Chapter 3 



Soil Erodibility Analysis 



Soil erosion is important because it reduces productivity 
of agricultural lands and because eroded soil can be 
transported to a stream where it becomes sediment. 
Topsoil is expensive to replace and natural soil-forming 
processes would require thousands of years to replenish 
soil already lost from the Nation's farmland. One of the 
tools developed by agricultural scientists to estimate soil 
loss from farm lands is the Universal Soil Loss Equation, 
or USLE. The USLE is intended to demonstrate how 
agricultural practices contribute to or reduce soil erosion. 
The USLE is not generally applied to nonfarm land cover 
types. 

Figure 3.22 shows the watershed classes for the different 
USLE K-factor erodibility values assigned to the surface 
soil horizons. The K-factor estimates the relative erodibil¬ 
ity of a soil with respect to all possible textures (range 0.0 
to 0.64). Surface soils in the Tensas River Basin exhibit 
K-factors ranging from 0.18 to 0.48. As shown in the 
figure, the most erodible soils seem to occur most com¬ 
monly in old oxbows and meander channels and are 
spread evenly throughout the Basin. The least erodible 
soils occur in backswamp areas adjacent to active 
stream channels. 


K-factor 
; Water 
0.18- Low 
0.21 
0.27 
0.28 
0.29 
0.3 
0.31 
0.32 

m 0-35 
0.38 

0.4 
0.41 
0.45 

0.48-High 


Figure 3.22 

Relative Soil Erodibility Map for Tensas River Basin. 
Source: NRCS STATSGO. 
























An Ecological Assessment of the Louisiana Tensas River Basin Chapter 3 





Wetland Restoration Analysis 

Restoration of wetlands and associated processes is a 
primary objective of many of the stakeholders in the 
Tensas River Basin. As a result, the Tensas River Basin 
has been the focus of many environmental studies which 
provide many types of data to continue our analysis. Many 
GIS coverages are readily available from groups involved in 
previous and ongoing studies. These resources provided 
the opportunity to use this data along with the forest 
change data to evaluate potential wetland restoration. One 
of the GIS databases available covers all the areas which 
are a part of the Louisiana Private Lands Restoration - 
Wetland Reserve Program. These are areas where land 
owners have changed land use from agriculture back to 
forests. Figure 3.23a shows restoration efforts that have 


been taking place over the past 5 years around the Tensas 
River Basin. This image shows that the areas previously 
selected for forest restoration were suitable in terms of 
restoring forests along riparian areas and connecting 
existing forests. Figure 3.23b is a view of the forest 
change, wetland restoration sites and streams to better 
show how the forest restoration sites are suitable in terms 
of restoring forest along riparian areas and connecting 
existing forests. 

Displaying GIS databases and remote sensing data 
together can visually give land managers more information 
about soils, flood potential, and other types of features to 
help make the best choices for restoration. 



Figure 3.23a 

Wetland Reserve Program (WRP). 
Remote Sensing Image 


















Using the landscape analysis indicator of percent forest, 
Table 3.8, we recalculate the landscape statistics to 
include the Wetland Restoration data. The results of this 
analysis are shown in Table 3.8. Table 3.8 provides a 
statistical view of the Tensas Basin in 20 years or when the 


trees have grown enough to establish a forested area. It is 
interesting to note that most of the restoration efforts have 
gone into the subwatersheds 4 and 7. Using the data from 
this analysis future decisions in selecting restoration sites 
land managers may want to focus more attention to 
subwatersheds 8 and 9. 










































An Ecological Assessment of the Louisiana Tensas River Basin Chapter 3 





Through landscape analysis we can also locate sites for 
potential forest wetland restoration. Figure 3.24 shows a 
combination of a hydric soils map with a flood map and 
the forest change map along a 360-meter buffer of the 
main channel of the Tensas River Basin and its major 
tributaries. Using these maps land managers can make 
decisions on locating potential restoration sites by factor¬ 
ing in fertile and non-fertile soil types, land which has the 
potential to flood, and areas which were forest and could 
easily be forested again in the future. Based on the 
combinations of these indicators, the best candidates for 
potential restoration sites are shown in green on the right 
image of Figure 3.24. Figure 3.24 shows an enlarged 
map for ease in identifying restoration locations. Figure 


3.25 illustrates this technique applied over the entire Basin. 

We have also determined the percent of forest change 
including restoration efforts over the Tensas River Basin 
and its subwatersheds. Figure 3.26 shows the percent of 
forest change, the forest change for the whole basin, and 
the net forest restoration effort to date. Zones 4 and 7 
show the most impact from the restoration efforts and 
Zones 6, 8, and 9 show little change in restoration. Zone 8 
shows the most forest loss of all the Zones with a 21.2 
percent loss over the 20-year time period. The combina¬ 
tion of GIS analysis and these kinds of landscape analysis 
can give land managers powerful decision tools for improv¬ 
ing environmental quality. 





Flooded Ares* 



Figure 3.24 



Potential Forest Wetland Restoration. 


Areas of Potential Resoration - 
Combination of Forest Loss and Flooded 
Areas Displayed on Hydric Soils. 


Potential Restoration 

A/ Tensas River 
Soils - Percent Hydric 
33-51% 

52 - 82% 

83 - 99% 


Forest Loss/Gain - 
Within 360 meter Buffer 
of the Tensas River and 
Major Tributaries 


Land cover 
Forest 
Forest Loss 
Forest Gain 
Human Use 
■H Water 































An Ecological Assessment of the Louisiana Tensas River Basin Chapter 3 




5 0 5 10 Miles 


Restored Forest Sites 
Proposed Sites 
Roads 
Streams 

Watershed Boundaries 


Figure 3.25 Potential Forest Wetland Restoration for the 
Entire Tensas River Basin 























Loss (%) Ga i n (%) 


An Ecological Assessment of the Louisiana Tensas River Basin Chapter 3 


25 

20 

15 

10 


mm 


Percent Forest Gain 

Percent Forest Loss 

Net Forest Change 

Projected Gain from Restoration 

Projected Net Forest Change with Restoration 



Tensas River Basin Zones 


Figure 3.26 
































































Table 3.1 1972 Forest 


An Ecological Assessment of the Louisiana Tensas River Basin Chapter 3 


X 

o 











J= 

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136.6 

70 

54.7 

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54939.2 

36.4 

311.0 

13117.0 

17871.5 

6999.1 

4276.1 

19221.5 

3021.8 


Largest 

Patch (ha) 

37997.3 

87.1 

132.5 

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00 

8953.9 

4727.9 

4027.0 

10336.7 

2382.5 

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(prxels) 

152609 

101 

864 

36436 

49643 

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00 

00 

53393 

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(pixels) 

105548 

242 

368 

11614 

24872 

13133 

11186 

28713 

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(pixels) 

00 

rs 

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712 

5403 

61666 

84382 

21398 

12354 

108326 

57279 


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(pixels) 

224465 

1056 

3872 

31199 

57244 

vO 

00 

00 

12266 

61431 

39231 


375834.2 











375821.3 









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5604.8 

45388.1 

92480.8 

61773.8 

11127.6 

7348.0 

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72221.4 

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15558 

126080 

256905 

171571 

30923 

20413 

221446 

200602 































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Table 3.3 Forest Change 


An Ecological Assessment of the Louisiana Tensas River Basin Chapter 3 






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375806.5 

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92471.0 

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11126.2 

7345.8 

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1043907 

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31302 

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Table 3.5 360 Meter Buffer along the Tensas River 



An Ecological Assessment of the Louisiana Tensas River Basin Chapter 3 



4-1 C/2 O n 

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(pixels) 

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3229 

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Total # o 
Pixels 

691533 

6071 

67779 

178889 

56051 

30904 

4164 

199037 

148346 

8 

o 

3 

o 

cm 

r*D 


CD 

NO 


00 

ON 

N 

H 



















































Table 3.7 Forest Backswamp Change 



An Ecological Assessment of the Louisiana Tensas River Basin Chapter 3 
















a xo 
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rest Loss 
[pixels) 

22824 

26 

478 

6069 

3704 

160 

NO 

(n 

4544 

6840 

0 










u. 










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a 

0 

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Total (ha 

45157.0 

941.8 

2521 8 

12104.3 

8342.3 

813.2 

1175.8 

7395.5 

11871 4 


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n 









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n 

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(pixels) 

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3140 

33844 

30119 

3294 

1448 

51239 

24496 



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Total n of 
Pixels 

1043906 

15559 

126076 

256865 

171511 

30904 

20405 

221426 

200588 

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An Ecological Assessment of the Louisiana Tensas River Basin Chapter 4 



Chapter 4: Water Quality 


Perceived problems with water quality have been an 
issue in the Tensas River Basin. The approach taken 
here to examining water quality was to first gather all the 
stream water quality data available and then to analyze it 
both temporally and spatially. Initially the hope was to 
gather enough data to be able to associate water quality 
with some of the landscape metrics discussed previously. 

The major source of the data was STORET, the EPA 
water quality data base. Not only is the EPA data stored 
in this data base but so is data from the USGS and 
various states including Louisiana. All of the existing 
water quality data for the Tensas River Basin was re¬ 
quested. It was then verified with Louisiana Department 
of Environmental Quality (LDEQ) and USGS that all 
existing water quality data for the basin were contained in 
the storet data base. 


The water quality data search yielded a data set that 
included stream water quality data from 17 stations. 
However many of these stations included only data from 
a one-time sampling effort often dating back to the 1970s 
or the station ceased to operate in the 1970s or early 
1980s. The criterion for using a station’s water quality data 
required that it have data from the 1990s or it be located 
close to a station that had data from the 1990s. This 
criteria was selected as these would be the most relevant 
data to current conditions in the Tensas River Basin. This 
criteria limited the data available for analysis to three sites; 
Tendal, Winnsboro, and Clayton. The locations of these 
stations are shown in Figure 4.1. Both Louisiana state 
and the USGS collect samples from Tendal and Clayton. 
Unfortunately, with a sample number of only three water 
quality monitoring stations, it is impossible to make valid 
associations between the water quality data and any of the 
landscape metrics that was previously presented. In 
addition to the three stream monitoring stations, water 
quality data from Lake Providence were also retrieved. 
This lake in the Tensas Bayou serves as the headwaters 
of the Tensas River. 

This analysis focused on two variables: total phosphorus 
and total nitrogen as nitrite and nitrate. In the analysis of 
the data, significant differences between the three stations 
were examined as well as seasonal differences and trends 
over many years. 


Figure 4.2 shows the seasonal distribution of the 
nitrogen and phosphorus data from 1990 through 1996 
for all three LDEQ water quality monitoring stations. This 
type of display is known as a box and whisker plot. The 
top and bottom edges of the blue box represent the 25th 
and 75th percentiles of the distribution of the data (i.e., 
50% of the data values fall within this range). The vertical 
lines extend from the blue box down to the 10th and up 
to the 90th percentile (i.e., 80% of the data values fall 
within this range). 



Figure 4.1 

Location of Tensas River Basin Water Quality Monitoring Stations. 























An Ecological Assessment of the Louisiana Tensas River Basin Chapter 4 



The small horizontal line drawn within the blue box 
indicates the median value. Any value outside of the 
10th and 90th percentiles is displayed on the graph as a 
light blue dot. This type of display was chosen rather 
than a simple mean ± standard deviation plot because a 
normality test indicated that many of the data distribu¬ 
tions for a given station or season were not normally 
distributed. In part due to the low sample numbers, 
which are indicated above the box and whisker illustra¬ 
tion, a mean value would be heavily influenced by outlier 
values. One extreme outlier nitrogen value of 5.9 mg/L 
was omitted from Figure 4.2 for the summer season from 
the Tendal station. This outlier, omitted for display pur¬ 
poses only, was included in the calculations in the sum¬ 
mary statistics given in the Appendix. 

Figure 4.2 shows seasonal differences exist for both 
nitrogen and phosphorus concentrations for all three 
stations with the exception of phosphorus concentra¬ 
tions from the Tendal station. In general, nutrient 
concentrations decline from the spring through the fall 
and then start increasing again in the winter. It is 
interesting that the Tendal station does not seem to 
fluctuate seasonally nearly as much as do the other two 
stations. Perhaps, this phenomenon is due to the 
proximity of agricultural fields to the water quality moni¬ 
toring station. Statistical summaries of the water quality 
data from the LDEQ stations can be found in the Appen¬ 
dix. 

To determine whether there were significant differences 
between the three stations, a Wilcoxon rank-sum (also 
known as Mann-Whitney U) test was performed. Again, 
a nonparametric statistic was used because the data 
are not normally distributed and the sample numbers 
are low. There were no significant differences between 
all three stations for total nitrogen. This was true for all 
seasons combined and for individual seasons. For total 
phosphorus there were statistically significant differ¬ 
ences between Tendal and Clayton and between 
Tendal and Winnsboro when all seasons were 
combined. When this analysis was performed on 
individual seasons, there were statistically significant 
differences between Tendal and Clayton for the summer 
and the fall and there were significant differences be¬ 
tween Tendal and Winnsboro for the fall. All other 
comparisons of station and season yielded nonsignifi¬ 
cant differences. A summary of this analysis is included 
in the Appendix. 


Figures 4.3 through 4.5 show the historical total nitrogen 
concentrations for all three locations on separate graphs. 
Figures 4.6 through 4.8 show the historical total phos¬ 
phorus concentrations. When there is a LDEQ station 
collocated with a USGS station, the points are plotted 
with different color symbols. It would appear that both 
nitrogen and phosphorus concentrations have increased 
slightly for the Clayton station when comparing data from 
the 1970s to the 1990s. It should be noted however that 
the data from the 1970s were exclusively collected by the 
USGS while the data from the 1990s were exclusively 
collected by LDEQ. It may not be appropriate to compare 
these data directly as there may have been differences in 
methodology. 

It is also interesting to compare the water quality from the 
three stream monitoring stations to the water quality in 
Lake Providence (Figures 4.9 and 4.10). Lake Provi¬ 
dence serves as the headwaters of the Tensas River and 
clearly the nitrogen and phosphorus levels are lower than 
they are at Tendal, Winnsboro, or Clayton. 

When evaluating the quality of the water in the Tensas 
River, one should look at how the data compare with any 
established criteria. To limit eutrophication potential to 
downstream waters, the EPA Quality Criteria for Water 
(1986) advises that total phosphorus levels should not 
exceed 0.1 mg/ L. This is also the criteria used by the 
EPA's Surf Your Watershed program. Clearly many of the 
values from the Tensas River samples exceed that level. 
We were unable to find a total nitrogen criteria for surface 
water. 

In summary the following can be said about nutrient 
levels in the Tensas River: They are higher in the stream 
water than they are in the headwaters, they are generally 
seasonal in nature, phosphorus levels are at a level 
where they could contribute to eutrophication, and there 
are some significant differences in phosphorus levels 
between Tendal and the other two monitoring stations. 

To perform a more thorough investigation of the water 
quality in the Tensas River Basin, a comprehensive water 
quality study that would characterize the water quality of 
all the subwatersheds within the basin should be de¬ 
signed and conducted. 



















Total Phosphorus (mg/L) Tot a I Nitrogen (mg/L) as ND2 & N03 



An Ecological Assessment of the Louisiana Tensas River Basin Chapter 4 




Figure 4.2 Total nitrogen and phosphorus concentrations for three Louisiana state water quality monitoring stations in 
the Tensas River Basin. Data displayed are from those samples collected 1990- 1996. The top and bottom edges 
of the light blue box represent the 25th and 75th percentiles of the distribution of the data (i.e., 50% of the data values 
fall within this range). The horizontal line drawn within the blue box represents the median value. The vertical 
lines extend to the 10th and 90th percentile. Any value outside of this range is displayed on the graph as a light 
blue dot. The number of data points included in the analysis is printed above each box. 










































































Total Nitrogen (mg/L) as ND2 & ND3 Total Nitrogen (mg/L) as ND2 & N03 



An Ecological Assessment of the Louisiana Tensas River Basin Chapter 4 




Sample Collection Date 

STATION • • • 07369500 • • • 58010066 

Figure 4.3 Total nitrogen concentrations for two water quality monitoring stations in Tendal, La. 


3.0 

2.5 

2.0 

1.5 

1.0 

0.5 

0.0 

02/12/90 11/08/92 08/05/95 05/01/98 



Sample Collection Date 
STATION • • • 58010331 

Figure 4.4. Total nitrogen concentrations for Winnsboro, La. 














Total Phosphorus (mg/L) Total Nitrogen (mg/L) as ND2 & N33 


An Ecological Assessment of the Louisiana Tensas River Basin Chapter 4 



Sample Collection Date 

STATION • • • 07370190 • • • 58010159 

Figure 4.5 Total nitrogen concentrations for two water quality monitoring stations in Clayton, LA 



Sample Collection Date 

STATION • • • 07369500 • • • 58010066 

Figure 4.6 Total phosphorus concentrations for two water quality monitoring stations inTendal, LA 


















Total Phosphorus (mg/L) Total Phosphorus (mg/L) 


An Ecological Assessment of the Louisiana Tensas River Basin Chapter 4 



— 



Sample Collection Date 
STATION • • • 58010331 

Figure 4.7 Total phosphorus concentrations for Winnsboro, LA 



Sample Collection Date 

STATION • • • 07370190 • • • 58010159 

Figure 4.8 Total phosphorus concentrations for two water quality monitoring stations in Clayton, LA 













Total Phosphorus (mg/L) Total Nitrogen (mg/L) as ND2 & ND3 


An Ecological Assessment of the Louisiana Tensas River Basin Chapter 4 





Sample Collection Date 
STATION • • • 58010132 

Figure 4.9 Total nitrogen concentrations for Lake Providence at Tensas Bayou 



Sample Collection Date 
STATION • • • 58010132 

Figure 4.10 Total phosphorus concentrations for Lake Providence at Tensas Bayou 




















EH 


An Ecological Assessment of the Louisiana Tensas River Basin Chapter 4 


m 




Nitrogen and Phosphorus Export to Streams 

Despite the many benefits, there is a potential negative 
impact of fertilizer application on agricultural fields. The 
problem was first identified decades ago as part of the 
study of lake eutrophication. Lake eutrophication is a 
process by which excess nutrients in lake water make it 
easier for undesirable plants to thrive, which in turn 
consume other resources and adversely affect lake water 
quality for other purposes. The potential effects of the 
export of nitrogen and phosphorus from farmlands to 
streams have been intensively studied for several de¬ 
cades. It is now possible to survey the scientific literature 
to determine how much nitrogen and phosphorus export 
can be expected for different types of land uses in 
different areas. 

A literature survey of North American nutrient export 
studies (Young and others, 1996, in the Journal of 
Environmental Management) provided coefficients for 
estimated export (kg/ha/yr) for nitrogen and phosphorus 
under different types of land uses. To estimate total 
nutrient export potential on the Tensas River Basin, the 
reported median coefficients for comparable agricultural 
uses were multiplied by the amount of land cover in the 
agriculture land cover classes. The coefficient-times-land 
use model was developed in 1980 for the United States 
Environmental Protection Agency by Rechow and others 
(US EPA 440/5-80-011, Washington, DC). The coeffi¬ 
cients reported for nitrogen varied from 2.6 to 6.2 kg/ha/ 
yr, with a median value of 3.9 kg/ha/yr. The values 
reported for phosphorus ranged from 0.3 to 1.5 kg/ha/yr, 
with a median value of 0.7 kg/ha/yr. 

The scientific literature provides a simple predictive 
model based only on nitrogen and phosphorus loadings 
to streams. Of course, this model does not reflect actual 
fertilizer application rates which determine local export 
amounts. However, over an area such as the Tensas 
River Basin, the models are valuable as a screening tool 
to rank subwatersheds based on potential impacts, 
assuming that average fertilizer rates are used through¬ 
out the region. In a nutshell, if there are no agricultural 
lands in a watershed, then fertilizer application is near 
zero. Such a watershed has less risk of impacts than a 
watershed for which 30 percent of the area is used for 
agriculture. One major drawback of this simple model is 
that it ignores fertilizer applications in urban areas, where 
areas such as lawns, gardens, and golf courses can 
receive heavy fertilizer doses several times a year. 


When this model was applied to the Tensas River Basin 
the potential nitrogen loading was 4.96 kg/ha/yr and the 
potential phosphorus loading was 1.34 kg/ha/yr. These 
are very high values when compared to values found 
elsewhere in the U.S. These values were calculated 
from the agricultural landuse data shown in the landcover 
data in Chapter 3 (Figure 3.4). These data show 
225,708 hectares of land used for intensive agriculture, 
which does not include grasslands for grazing, orchards, 
and vegetation in towns. This is 60% of the total land 
area which is consistent with the human use index 
shown in Chapter 3 (Figure 3.6). Again, this model only 
shows the amount of nitrogen and phosphorus that may 
be available for transport into the water system. 






An Ecological Assessment of the Louisiana Tensas River Basin Chapter 5 


Chapter 5: Comments 
Recommendations 


There are many fine features which make up the 
Tensas River Basin. Fertile farmlands, deep forests 
and abundant wildlife form the basis of the good life 
provided by the land near the Tensas River. The 
continued good health of the Tensas River Basin 
depends on how the land is used. The health of the 
basin should be of concern to everyone living there 
because their livelihood depends on what the land 
can provide. Efforts to practice Best Farming Prac¬ 
tices and the steps taken to restore forested wet¬ 
lands in the Tensas River Basin are a big step in the 
direction of keeping the Tensas healthy. A healthy 
Tensas River providing clean water and sound prod¬ 
ucts will also benefit those living down stream and 
can improve the quality of the Gulf of Mexico. 

This chapter draws comments and recommenda¬ 
tions from what was learned from the landscape 
analysis of the Tensas River Basin. Two of the main 
concerns of land management and environmental 
monitoring and protection are determining whether 
environmental features are changing (for better or 
worse) and determining whether management and 
protection practices are working effectively. These 
are complex issues. While the landscape analysis 
performed in this atlas begins to address these 
questions, it is only a beginning and is only part of the 
scientific work needed to answer complex ecological 
questions. 


Comments 

The forest loss over the time period studied was 
remarkable. Forest loss of this magnitude is bound 
to have an effect on environmental quality. Much of 
the lost forest was converted to agriculture making 
human use of the land very high in most of the 
subwatersheds. High intensity agriculture makes 
use of fertilizer. The landscape model showing the 
potential for nutrient (nitrogen and phosphorus) 
loading is high when compared to other watersheds 
throughout the United States. Although most of the 
fertilizer applied is effectively used to grow a good 
crop, it is virtually unavoidable that some of the 
fertilizer will run off the land. The fertilizer which 
does run off can be intercepted by natural vegetation 
but when this vegetation is gone, excess fertilizer 
can run directly into the water and be carried down 
stream. 


and 


The land of the Tensas River Basin is flat. Water 
moves slowly compared to a river located in the 
mountains. Water flow is driven by events such as 
rain storms and hurricanes. Water and nutrients can 
be held in swamp areas only to be flushed out during 
high precipitation events. The natural vegetation 
located in the backswamp areas can be as or more 
important in holding excess nutrients than the vegeta¬ 
tion located near the stream. 

The landscape analyses demonstrated that since 
1972 the forest was lost around the forest edges and 
generally not separated into small patches. Forest 
patch size was maintained so that in the event of 
stress to the forest (fire or flood) the forest and forest 
wildlife should be able to reestablish itself in a robust 
manner. Looking at the forest restoration efforts 
indicated that very wise decisions were made in the 
locations of forests reestablishment. Areas chosen 
included riparian areas, backswamp areas and areas 
which connected forest patches. Hopefully this land¬ 
scape assessment can verify that the correct deci¬ 
sions were made, reveal how the forest changes will 
look when the trees have matured, and identify addi¬ 
tional areas to restore. It also showed that little or no 
restoration efforts are underway in the southern part of 
the watershed. Using Best Farming Practices to 
reduce fertilizer runoff combined with forest restora¬ 
tion should make a positive impact on the quality of 
water and the quality of the land. 



Figure 5.1 The Tensas River Winter 1997-1998 




























64 


An Ecological Assessment of the Louisiana Tensas River Basin Chapter 5 




_ 


Tensas River Basin 
Landscape Indicator Analysis 


Sub- 

basin 

U-Index 

Roads 

Km/Km 2 

<3 

# Roads 
Crossing 
Streams 

Forest 

Fragmentation 

Forest 

Change 

NDVI 

Change 

Riparian 

Forest 

Change 

Back- 

swamp 

Forest 

Change 

Forest 

Change 

with 

Restoration 

1970 

1990 

1970 

1990 

All 

65.0 

77.2 

0.98 

0.28 

88.7 

84.5 

-12.3 

-11.4 

-14.4 

-14.6 

-11.1 

2 

85.2 

82.3 

1.49 

0.32 

43.9 

53.8 

1.7 

-8.5 

1.7 

3.7 

1.7 

3 

95.3 

96.6 

1.07 

0.35 

48.4 

48.3 

-1.4 

-8.1 

-1.0 

-2.5 

-1.2 


75.5 

87.5 

1.03 

0.31 

86.2 

76.6 

-12.1 

-11.4 

-15.5 

-17.9 

-8.6 

5 

49.9 

66.0 

0.80 

0.19 

93.0 

91.8 

-16.1 

-11.7 

-16.3 

-13.6 

-15.3 

6 

30.0 

38.9 

0.42 

0.07 

95.2 

94.9 

-8.8 

-5.5 

-8.8 

-3.9 

-8.8 

7 

38.3 

39.0 

0.87 

0.27 

87.2 

88.1 

-1.0 

-3.7 

7.2 

-5.5 

6.4 

8 

48.5 

69.6 

0.98 

0.28 

90.3 

85.3 

-21.2 

-18.7 

-23.7 

-18.4 

-21.2 

9 

69.9 

78.9 

1.06 

0.33 

80.9 

75.0 

-9.2 

-6.9 

-8.4 

-15.4 

-9.2 


Table 5.1 gives'a summary of all the landscape indicators given in this report. The colors along with the values represent the Tensas River Basin’s 
ecological condition. Red for concern, yellow for caution, and green for sound. 


Recommendations 

There are many more types of landscape analyses 
which could be done to provide information to land 
managers, farmers and environmental quality special¬ 
ists. The landcover map shown in Chapter 3 (Figure 
3.4) could be used to perform much more detailed 
analysis investigating different types of agricultural 
use. These data could be analyzed to further identify 
locations of landuse and landcover in relation to 
features on the landscape. If wildlife species-spe¬ 
cific questions arise, these data can be used to 
model habitat requirements. For example, if a given 
species requires a certain size forest patch and has a 
distance to water requirement, the data can be que¬ 
ried to identify land parcels that meet those require¬ 
ments. 


As discussed in Chapter 3 in the Wetland Restoration 
section, the data layers included in this data set can 
be used to help identify sites for potential wetland 
forest restoration. The data can be queried based on 
a set of “rules” defined by local land managers, 
farmers, and environmental quality specialists. For 
example, one could identify (as we did in Chapter 3) 
all patches of land within 360 meters of the Tensas 
River that are currently agriculture but were histori¬ 
cally forested, have hydric soils, and have a high 
potential to flood. Perhaps current agricultural use 
would be a factor. Maybe it would be more economi¬ 
cally feasible to convert land from one type of agricul¬ 
tural use that it would from another (e.g., more 
economical to convert from soybean than from rice). 






































Using the forest change data, all of the landscape 
indicator data and the landuse/landcover data, more 
analyses could be done on comparing the 
subwatersheds to each other. Indicators such as U- 
index, roads crossing streams, forest loss and nutri¬ 
ent loading could be used to rank the subwatersheds. 
This would be used to target landuse practice 
changes to areas most in need. 

The North American Landscape Characterization 
image database provides 20 years of change detec¬ 
tion data. These data could be classified and used 
effectively to identify status and trends of landuse 
elsewhere in the Mississippi River Basin. The NDVI 
analysis was an informative, cost effective, and quick 
method for assessing ecological change detection for 
the Tensas River Basin. This method could also be 
developed and used to characterize ecological 
changes for the entire Mississippi River Basin or to 
target areas that need further analysis using tradi¬ 
tional land classification methods. 


subwatershed have an affect on water quality. With 
an in-depth water quality study, not only would re¬ 
searchers be able to answer questions such as those 
posed above but the data would provide a baseline 
data base of water quality that could be used later to 
determine whether restoration and protections efforts 
made today have the desired effect in the future. 
Without this type of information, it will be difficult to 
determine how successful these efforts have been. 


"A system of conservation based solely on economic 
self-interest is hopelessly lopsided. It tends to ignore, 
and thus eventually to eliminate, many elements in the 
land community that lack commercial value, but that 
are (as far as we know) essential to its healthy func¬ 
tioning." 

-Aldo Leopold (father, farmer, and ecologist) 


Water quality continues to be an issue in the Tensas 
River Basin yet there is very little data available to 
adequately characterize water quality for the basin. 
This is particularly true when trying to link water 
quality with any of the landscape metrics discussed in 
this report. The water quality data presented in 
Chapter 4 is easy to use in terms of characterizing 
individual water quality monitoring stations but diffi¬ 
cult to use in terms of characterizing a subbasin or 
the entire Watershed. The present sampling loca¬ 
tions can detect the presence and quantity of nutri¬ 
ents but can’t tell you if one subbasin or area is 
1 contributing more or less than another. We feel that a 
well-designed water quality study would add a wealth 
of information to the data available for the Tensas 
i River Basin. This study should be designed and 
implemented to characterize each subwatershed 
along with the entire Tensas River Basin using ran¬ 
domized sampling techniques stratified within the 
subwatersheds. With this type of information, there 
are many questions that could be answered such as: 
do certain types of agriculture affect the Tensas River 
nutrient loads more that others; does landuse (forest 
. cover or agricultural) in backswamps or riparian areas 
have an effect on the flow of nutrients; does landuse 
in the 



Figure 5.2 Airphoto of the Tensas River near Westwood, LA 



























Appendix: Additional Information About 

the Tensas River Basin 


Tensas River Basin - Forest Change Analysis for the 1970 Classification 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

3 types found. 

1043984 pixels (non-missing). 

2256364 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

2 

679228 

0.65061 

1 

350828 

0.33605 

3 

13928 

0.01334 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

2 

1393704 

0.939641 

1 

742606 

0.886800 

3 

34785 

0.591778 

Patch Statistics 

Data code 

Number 

Largest 

N patches 

Avg patch 

Proportion 


patches 

patch 

<5 cells 

size 

5 

2 

1066 

621658 

779 

637.174 

0.9982 

1 

3248 

152609 

2159 

108.014 

0.9897 

3 

878 

2969 

673 

15.863 

0.9219 

Overall values, not area-weighted: 






5192 

621658 


201.076 

0.9943 


T3L TCL701.wpd -078Leb98 


LEGEND 


1: Forest; 


2: Human Use; 


3: Water 





































































Tensas River Basin - Forest Change Analysis 1970 Class Subwatershed 2 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analy7pr 

3 types found. 

15569 pixels (non-missing). 

13339 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

2 

13267 

0.85214 

1 

712 

0.04573 

3 

1590 

0.10213 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

2 

26724 

0.952253 

1 

1973 

0.439432 

3 

3413 

0.846469 

Patch Statistics 

Data code 

Number 

Largest 

N patches 

Avg patch 

Proportion 


patches 

patch 

<5 cells 

size 

5 

2 

24 

13159 

15 

552.792 

0.9978 

1 

93 

101 

67 

7.656 

0.8666 

3 

8 

1564 

3 

198.750 

0.9975 

Overall values, not area-weighted: 






125 

13159 


124.552 

0.9918 


LEGEND 


T3L TCL702.wpd -078Leb98 


1: Forest; 


2: Human Use; 


3: Water 













































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 




i 


Tensas River Basin - Forest Change Analysis 1970 Class Subwatershed 3 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

3 types found. 

126078 pixels (non-missing). 

115728 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

2 

120252 

0.95379 

1 

5403 

0.04285 

3 

423 

0.00336 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

2 

242246 

0.969626 

1 

14325 

0.484328 

3 

1169 

0.426005 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

2 

37 

120166 

31 

3250.054 

0.9997 

1 

746 

864 

597 

7.243 

0.8286 

3 

78 

155 

67 

5.423 

0.7754 

Overall values, not area-weighted: 

861 120166 146.432 0.9916 


LEGEND 


T3L TCL703.wpd -078Leb98 


1: Forest; 


2: Human Use; 


3: Water 



























































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 




Tensas River Basin - Forest Change Analysis 1970 Class Subwatershed 4 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analy7er 

3 types found. 

256891 pixels (non-missing). 

235912 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

2 

193968 

0.75506 

1 

61666 

0.24005 

3 

1257 

0.00489 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

2 

395488 

0.954090 

1 

131605 

0.862444 

3 

3259 

0.505370 

Patch Statistics 

Data code 

Number 

Largest 

N patches 

Avg patch 

Proportion 


patches 

patch 

<5 cells 

size 

5 

2 

191 

190513 

142 

1015.539 

0.9987 

1 

788 

36436 

529 

78.256 

0.9854 

3 

165 

297 

137 

7.618 

0.8282 

Overall values, not area-weighted: 






1144 

190513 


224.555 

0.9947 


LEGEND 


T3L TCL704.wpd -078Leb98 


1: Forest; 


2: Human Use; 


3: Water 





















































































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 






Tensas River Basin - Forest Change Analysis 1970 Class Subwatershed 5 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

3 types found. 

171594 pixels (non-missing). 

409844 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

1 

84382 

0.49175 

2 

85707 

0.49948 

3 

1505 

0.00877 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

1 

173218 

0.930307 

2 

174895 

0.932977 

3 

3482 

0.430213 

Patch Statistics 

Data code 

Number 

Largest 

N patches 

Avg patch 

Proportion 


patches 

patch 

<5 cells 

size 

5 

1 

449 

49643 

279 

187.933 

0.9940 

2 

226 

39931 

168 

379.235 

0.9968 

3 

235 

95 

155 

6.404 

0.8246 

Overall values, not area-weighted: 






910 

49643 


188.565 

0.9939 


T3L TCL705.wpd -078Leb98 


LEGEND 


1: Forest; 


2: Human Use; 


3: Water 




























































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 



Tensas River Basin - Forest Change Analysis 1970 Class Subwatershed 6 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

3 types found. 

30910 pixels (non-missing). 

35042 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

1 

21398 

0.69227 

2 

9300 

0.30087 

3 

212 

0.00686 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

1 

42860 

0.952077 

2 

19261 

0.910025 

3 

509 

0.235756 

Patch Statistics 

Data code 

Number 

Largest 

N patches 

Avg patch 

Proportion 


patches 

patch 

<5 cells 

size 

5 

1 

132 

19442 

107 

162.106 

0.9920 

2 

68 

6530 

59 

136.765 

0.9909 

3 

99 

30 

93 

2.141 

0.3679 

Overall values, not area-weighted: 






299 

19442 


103.378 

0.9874 


T3L TCL706.wpd -078Leb98 


LEGEND 


1: Forest; 


2: Human Use; 


3: Water 



























































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 



Tensas River Basin - Forest Analysis 1970 Class Subwatershed 7 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

3 types found. 

20411 pixels (non-missing). 

30425 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

3 

246 

0.01205 

1 

12354 

0.60526 

2 

7811 

0.38269 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

3 

720 

0.298611 

1 

26329 

0.872498 

2 

16763 

0.799081 

Patch Statistics 

Data code 

Number 

Largest 

N patches 

Avg patch 

Proportion 


patches 

patch 

<5 cells 

size 

5 

3 

75 

38 

67 

3.280 

0.5650 

1 

124 

11878 

100 

99.629 

0.9870 

2 

84 

7163 

63 

92.988 

0.9853 

Overall values, not area-weighted: 






283 

11878 


72.124 

0.9812 


LEGEND 


T3L TCL707.wpd -078Leb98 


1: Forest; 


2: Human Use; 


3: W ater 
















































Tensas River Basin - Forest Change Analysis 1970 Class Subwatershed 8 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

3 types found. 

221441 pixels (non-missing). 

224103 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

1 

108326 

0.48919 

3 

5713 

0.02580 

2 

107402 

0.48501 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

1 

226751 

0.903630 

3 

13033 

0.692550 

2 

224181 

0.905822 

Patch Statistics 

Data code 

Number 

Largest 

N patches 

Avg patch 

Proportion 


patches 

patch 

<5 cells 

size 

5 

1 

974 

53393 

754 

111.218 

0.9892 

3 

322 

2952 

260 

17.742 

0.9249 

2 

559 

98811 

462 

192.132 

0.9935 

Overall values, not area-weighted: 






1855 

98811 


119.375 

0.9896 


T3L TCL708.wpd -078Leb98 


LEGEND 


1: Forest; 


2: Human Use; 


3: Water 

























































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 



Tensas River Basin - Forest Change Analysis 1970 Class Subwatershed 9 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

3 types found. 

200615 pixels (non-missing). 

505923 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

2 

140272 

0.69921 

1 

57279 

0.28552 

3 

3064 

0.01527 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

2 

290790 

0.914664 

1 

125715 

0.809879 

3 

8241 

0.475549 

Patch Statistics 

Data code 

Number 

Largest 

N patches 

Avg patch 

Proportion 


patches 

patch 

<5 cells 

size 

5 

2 

286 

113329 

199 

490.462 

0.9979 

1 

919 

8394 

600 

62.328 

0.9825 

3 

157 

643 

111 

19.516 

0.9445 

Overall values, not area-weighted: 






1362 

113329 


147.294 

0.9927 


LEGEND 


T3L TCL709.wpd -078Leb98 


1: Forest; 


2: Human Use; 


3: Water 













































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 



Tensas River Basin - Forest Change Analysis for the 1990 Classification 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analvzer 

3 types found. 

1043948 pixels (non-missing). 

2256400 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

2 

806490 

0.77254 

1 

224465 

0.21502 

3 

12993 

0.01245 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

2 

1643483 

0.954937 

1 

484982 

0.845994 

3 

31735 

0.621932 

Patch Statistics 

Data code 

Number 

Largest 

N patches 

Avg patch 

Proportion 


patches 

patch 

<5 cells 

size 

5 

2 

753 

750008 

561 

1071.036 

0.9989 

1 

3488 

105548 

2364 

64.353 

0.9825 

3 

691 

3036 

465 

18.803 

0.9423 

Overall values, not area-weighted: 






4932 

750008 


211.668 

0.9947 


T3LTCL.901. wpd - 078L eb98 


LEGEND 


1: Forest; 


2: Human Use; 


3: Water 































































Tensas River Basin - Forest Change Analysis 1990 Class Subwatershed 2 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

3 types found. 

15 558 pixels (non-missing). 

13350 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

2 

12809 

0.82331 

1 

1056 

0.06788 

3 

1693 

0.10882 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

2 

25848 

0.953536 

1 

2728 

0.538123 

3 

3521 

0.867367 

Patch Statistics 

Data code 

Number 

Largest 

N patches 

Avg patch 

Proportion 


patches 

patch 

<5 cells 

size 

5 

2 

26 

12695 

18 

492.654 

0.9977 

1 

75 

242 

48 

14.080 

0.9375 

3 

5 

1582 

3 

338.600 

0.9965 

Overall values, not area-weighted: 






106 

12695 


146.774 

0.9935 


T3 L TCL902. wpd - 078Leb98 


LEGEND 


1: Forest; 


2: Human Use; 


3; Water 












































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 



Tensas River Basin - Forest Change Analysis 1990 Class Subwatershed 3 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

3 types found. 

126080 pixels (non-missing). 

115726 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

2 

121907 

0.96690 

1 

3872 

0.03071 

3 

301 

0.00239 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

2 

244617 

0.976800 

1 

10325 

0.483196 

3 

929 

0.290635 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

2 

83 

121748 

76 

1468.759 

0.9992 

1 

496 

368 

388 

7.806 

0.8355 

3 

82 

34 

68 

3.671 

0.6379 

• 

Overall values, not area-weighted: 

661 121748 190.741 0.9933 


T3 L TCL903.wpd - 078Leb98 


LEGEND 


1: Forest; 


2: Human Use; 


3: Water 



















































78 


An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 


Tensas River Basin - Forest Change Analysis 1990 Class Subwatershed 4 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

3 types found. 

256905 pixels (non-missing). 
v : 235898 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

2 

225015 

0.87587 

1 

31199 

0.12144 

3 

691 

0.00269 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

2 

456804 

0.963801 

1 

69663 

0.766648 

3 

2009 

0.367845 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

2 

123 

220608 

91 

1829.390 

0.9994 

1 

793 

11614 

507 

39.343 

0.9715 

3 

110 

51 

71 

6.282 

0.8336 

Overall values, not area-weighted: 

1026 220608 250.395 0.9955 


T3 L TCL904.wpd - 078Leb98 


LEGEND 


1: Forest; 2: Human Use; 3: Water 

























































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 



Tensas River Basin - Forest Change Analysis 1990 Class Subwatershed 5 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

3 types found. 

171571 pixels (non-missing). 

409867 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

2 

113185 

0.65970 

1 

57244 

0.33365 

3 

1142 

0.00666 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

2 

228851 

0.958877 

1 

117397 

0.918022 

3 

2657 

0.458412 

Patch Statistics 

Data code 

Number 

Largest 

N patches 

Avg patch 

Proportion 


patches 

patch 

<5 cells 

size 

5 

2 

125 

109734 

97 

905.480 

0.9987 

1 

535 

24872 

367 

106.998 

0.9889 

3 

162 

153 

116 

7.049 

0.8196 

Overall values, not area-weighted: 






822 

109734 


208.724 

0.9943 


T3L TCL905wpd - 078Leb98 


LEGEND 


1: Forest; 


2: Human Use; 


3: Water 






































































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 



Tensas River Basin - Forest Change Analysis 1990 Class Subwatershed 6 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

3 types found. 

30923 pixels (non-missing). 

35029 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

2 

12025 

0.38887 

1 

18864 

0.61003 

3 

34 

0.00110 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

2 

24805 

0.925257 

1 

37566 

0.949742 

3 

107 

0.271028 

Patch Statistics 

Data code 

Number 

Largest 

N patches 

Avg patch 

Proportion 


patches 

patch 

<5 cells 

size 

5 

2 

48 

8770 

34 

250.521 

0.9959 

1 

138 

13133 

107 

136.696 

0.9907 

3 

9 

13 

7 

3.778 

0.7353 

Overall values, not area-weighted: 






195 

13133 


158.579 

0.9925 


T3LTCL906.wpd - 078Leb98 


LEGEND 


1: Forest; 


2: Human Use; 


3: Water 






































































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 









Tensas River Basin - Forest Change Analysis 1990 Class Subwatershed 7 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

3 types found. 

20413 pixels (non-missing). 

30423 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

1 

12266 

0.60089 

2 

7962 

0.39005 

3 

185 

0.00906 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

1 

25914 

0.881223 

2 

17072 

0.816483 

3 

495 

0.298990 

Patch Statistics 

Data code 

Number 

Largest 

N patches 

Avg patch 

Proportion 


patches 

patch 

<5 cells 

size 

5 

1 

175 

11186 

144 

70.091 

0.9825 

2 

72 

6181 

52 

110.583 

0.9882 

3 

50 

37 

39 

3.700 

0.7081 

Overall values, not area-weighted: 






297 

11186 


68.731 

0.9822 


T3LTCL907.wpd- 078Leb98 


LEGEND 


1: Forest; 


2: Human Use; 


3: Water 











































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 



Tensas River Basin - Forest Change Analysis 1990 Class Subwatershed 8 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

3 types found. 

221446 pixels (non-missing). 

224098 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

1 

61431 

0.27741 

2 

154211 

0.69638 

3 

5804 

0.02621 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

1 

131713 

0.853325 

2 

316410 

0.941313 

3 

12986 

0.742030 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

1 

1123 

28713 

874 

54.703 

0.9774 

2 

368 

145233 

309 

419.052 

0.9969 

3 

268 

3014 

219 

21.657 

0.9388 

Overall values, not area-weighted: 

1759 145233 125.893 0.9900 


LEGEND 

1: Forest; 


T3 L TCL908. wpd - 078L eb98 


2: Human Use; 


3: Water 


























































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 




Tensas River Basin - Forest Change Analysis 1990 Class Subwatershed 9 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

3 types found. 

200602 pixels (non-missing). 

505936 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

2 

158225 

0.78875 

1 

39231 

0.19557 

3 

3146 

0.01568 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

2 

325007 

0.933106 

1 

88907 

0.750256 

3 

8482 

0.475949 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

2 

245 

130614 

179 

645.816 

0.9981 

1 

1047 

6618 

705 

37.470 

0.9699 

3 

193 

1065 

115 

16.301 

0.9406 

Overall values, not area-weighted: 

1485 130614 135.086 0.9917 


T3LTCL909.wpd- 078Leb98 


LEGEND 


1: Forest; 


2: Human Use; 


3: Water 












































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 



Tensas River Basin - Riparian Analysis 120 meter Buffer 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results .of Pixel Analyzer 

5 types found. 

691533 pixels (non-missing). 

2608815 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

5 

406345 

0.58760 

2 

112527 

0.16272 

1 

147034 

0.21262 

4 

13105 

0.01895 

9 

12522 

0.01811 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

5 

819978 

0.922619 

2 

246478 

0.800923 

1 

312040 

0.852474 

4 

39447 

0.266433 

9 

30836 

0.610455 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

5 

1752 

216825 

1203 

231.932 

0.9954 

2 

3758 

21183 

3002 

29.943 

0.9595 

1 

2673 

74997 

1930 

55.007 

0.9789 

4 

4459 

196 

3868 

2.939 

0.5519 

9 

808 

2998 

624 

15.498 

0.9206 

Overall values, not area-weighted: 

13450 216825 51.415 0.9763 


LEGEND 


T2L120.wpd - 078Leb98 


1: Forest; 


2: Forest Loss; 


4: Forest Gain; 


5: Human Use; 


9: Water 




















































































Tensas River Basin - Riparian Analysis Zone 2 120 meter Buffer 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

5 types found. 

6071 pixels (non-missing). 

22837 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

5 

4117 

0.67814 

2 

65 

0.01071 

1 

138 

0.02273 

4 

171 

0.02817 

9 

1580 

0.26025 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

5 

7312 

0.920268 

2 

197 

0.192893 

1 

382 

0.306283 

4 

431 

0.361949 

9 

3351 

0.862728 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

5 

59 

3508 

35 

69.780 

0.9840 

2 

31 

7 

26 

2.097 

0.4769 

1 

44 

29 

39 

3.136 

0.6014 

4 

43 

31 

35 

3.977 

0.6374 

9 

3 

1574 

1 

526.667 

0.9994 

Overall values, not area-weighted: 

180 3508 33.728 0.9641 


T2L120z2.wpd -078Leb98 


LEGEND 


1: Forest; 


2: Forest Loss; 


4: Forest Gain; 


5: Human Use; 


9: Water 





















































































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 




Tensas River Basin - Riparian Analysis Zone 3 120 meter Buffer 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results, of Pixel Analyzer 

5 types found. 

67779 pixels (non-missing). 

174027 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

5 

63736 

0.94035 

2 

1675 

0.02471 

1 

1282 

0.01891 

4 

992 

0.01464 

9 

94 

0.00139 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

5 

124010 

0.958269 

2 

4978 

0.281237 

1 

3352 

0.465394 

4 

2991 

0.265129 

9 

223 

0.358744 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

5 

131 

44560 

92 

486.534 

0.9977 

2 

557 

77 

494 

3.007 

0.5648 

1 

198 

229 

152 

6.475 

0.7956 

4 

356 

195 

322 

2.787 

0.5161 

9 

25 

27 

19 

3.760 

0.6702 

Overall values, not area-weighted: 

1267 44560 53.496 0.9757 


LEGEND 


T2L120z3.wpd -078Leb98 


1: Forest; 


2: Forest Loss; 


4: Forest Gain; 


5: Human Use; 


9: Water 






















































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 



Tensas River Basin - Riparian Analysis Zone 4 120 meter Buffer 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

5 types found. 

178889 pixels (non-missing). 

313914 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

2 

30382 

0.16984 

5 

123765 

0.69185 

4 

2677 

0.01496 

1 

21443 

0.11987 

9 

622 

0.00348 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

2 

66396 

0.811871 

5 

247653 

0.941265 

4 

8046 

0.237882 

1 

46917 

0.781593 

9 

1703 

0.369348 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

2 

931 

18102 

757 

32.634 

0.9609 

5 

310 

102728 

210 

399.242 

0.9972 

4 

979 

38 

831 

2.734 

0.5159 

1 

568 

11243 

389 

37.752 

0.9686 

9 

127 

113 

104 

4.898 

0.7379 

Overall values, not area-weighted: 

2915 102728 61.368 0.9795 


LEGEND 


T2L120z4.wpd -078Leb98 


1: Forest; 


2: Forest Loss; 


4: Forest Gain; 


5: Human Use; 


9: Water 


















































































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 



Tensas River Basin - Riparian Analysis Zone 5 120 meter Buffer 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

5 types found. 

56051 pixels (non-missing). 

525387 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

2 

10188 

0.18176 

5 

18202 

0.32474 

1 

25536 

0.45559 

4 

1072 

0.01913 

9 

1053 

0.01879 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

2 

20235 

0.831085 

5 

33670 

0.885061 

1 

49159 

0.919038 

4 

2833 

0.289799 

9 

2362 

0.455546 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

2 

294 

1722 

202 

34.653 

0.9664 

5 

247 

2394 

132 

73.692 

0.9886 

1 

251 

12462 

150 

101.737 

0.9898 

4 

365 

73 

320 

2.937 

0.5075 

9 

174 

95 

126 

6.052 

0.7854 

Overall values, not area-weighted: 

1331 12462 42.112 0.9721 


LEGEND 


T2L120z5.wpd -078Leb98 


1: Forest; 


2: Forest Loss; 


4: Forest Gain; 


5: Human Use; 


9: Water 














































































Tensas River Basin - Riparian Analysis Zone 6 120 meter Buffer 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

5 types found. 

30904 pixels (non-missing). 

35048 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

2 

3294 

0.10659 

5 

8736 

0.28268 

1 

18088 

0.58530 

9 

208 

0.00673 

4 

578 

0.01870 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

2 

7270 

0.794360 

5 

18187 

0.909441 

1 

36335 

0.941764 

9 

510 

0.233333 

4 

1680 

0.252976 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

2 

134 

2233 

113 

24.582 

0.9502 

5 

38 

6204 

30 

229.895 

0.9958 

1 

148 

12910 

124 

122.216 

0.9896 

9 

99 

30 

93 

2.101 

0.3462 

4 

220 

54 

201 

2.627 

0.5000 

Overall values, not area-weighted: 

639 12910 48.363 0.9736 


T2L120z6.wpd -078Leb98 


LEGEND 

1: Forest; 2: Forest Loss; 4: Forest Gain; 5: Human Use; 9: Water 

































































I 90 


An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 



Tensas River Basin - Riparian Analysis Zone 7 120 meter Buffer 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Resiilts.of Pixel Analyzer 

5 types found. 

4164 pixels (non-missing). 

46672 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

1 

832 

0.19981 

5 

2232 

0.53602 

9 

88 

0.02113 

2 

356 

0.08549 

4 

656 

0.15754 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

1 

1589 

0.643172 

5 

4113 

0.743010 

9 

232 

0.206897 

2 

858 

0.403263 

4 

1505 

0.390033 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

1 

89 

220 

65 

9.348 

0.8798 

5 

80 

1527 

55 

27.900 

0.9601 

9 

40 

10 

35 

2.200 

0.3864 

2 

88 

60 

78 

4.045 

0.6826 

4 

144 

59 

115 

4.556 

0.7332 

Overall values, not area-weighted: 

441 1527 9.442 0.8725 


LEGEND 


T2L120z7.wpd -078Leb98 


1: Forest; 2: Forest Loss; 4: Forest Gain; 5: Human Use; 9: Water 





































































Tensas River Basin - Riparian Analysis Zone 8 120 meter Buffer 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

5 types found. 

199037 pixels (non-missing). 

246507 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

1 

55256 

0.27762 

2 

50401 

0.25322 

5 

84262 

0.42335 

4 

3229 

0.01622 

9 

5889 

0.02959 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

1 

117407 

0.870348 

2 

109954 

0.827846 

5 

175871 

0.891574 

4 

10432 

0.200920 

9 

13355 

0.704231 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

1 

809 

27137 

650 

68.302 

0.9805 

2 

1260 

20356 

1080 

40.001 

0.9687 

5 

602 

63889 

475 

139.970 

0.9916 

4 

1382 

51 

1251 

2.336 

0.4230 

9 

338 

2956 

281 

17.423 

0.9221 

Overall values, not area-weighted: 

4391 63889 45.328 0.9714 


T2L120z8.wpd -078Leb98 


LEGEND 

1: Forest; 2: Forest Loss; 4: Forest Gain; 5: Fiuman Use; 9: Water 








































































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 





Tensas River Basin - Riparian Analysis Zone 9 120 meter Buffer 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

5 types found. 

148346 pixels (non-missing). 

558192 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

5 

99881 

0.67330 

2 

16982 

0.11448 

4 

4564 

0.03077 

1 

24001 

0.16179 

9 

2918 

0.01967 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

5 

205285 

0.899340 

2 

39785 

0.670806 

4 

13792 

0.264139 

1 

53387 

0.752861 

9 

7863 

0.467125 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

5 

565 

54525 

384 

176.781 

0.9942 

2 

1152 

2744 

896 

14.741 

0.9195 

4 

1574 

109 

1366 

2.900 

0.5537 

1 

936 

6286 

687 

25.642 

0.9560 

9 

209 

729 

152 

13.962 

0.9147 

Overall values, not area-weighted: 

4436 54525 33.441 0.9643 


LEGEND 


T2L120z9.wpd -078Leb98 


1: Forest; 


2: Forest Loss; 


4: Forest Gain; 


5: Human Use; 


9: Water 






























































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 



Tensas River Reach and Major Tributaries 
Riparian Analysis 360 Meter Buffer 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

5 types found. 

76659 pixels (non-missing). 

1720848 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

5 

39356 

0.51339 

1 

20793 

0.27124 

9 

4527 

0.05905 

2 

8883 

0.11588 

4 

3100 

0.04044 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

5 

78676 

0.841362 

1 

44387 

0.757406 

9 

12243 

0.470228 

2 

19844 

0.657327 

4 

9503 

0.260549 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

5 

367 

5116 

239 

107.237 

0.9911 

1 

647 

4686 

475 

32.138 

0.9621 

9 

307 

1343 

238 

14.746 

0.9123 

2 

665 

763 

505 

13.358 

0.9097 

4 

990 

131 

836 

3.131 

0.5842 

Overall values, not area-weighted: 

2976 5116 25.759 0.9527 


TBLM360j2.wpd - 078Leb98 

LEGEND: 1: Forest; 2: Forest Loss; 4: Forest Gain; 5: Fluman Use; 9: Water 









































































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 



Tensas River Basin - Backswamp Analysis 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

5 types found. 

125436 pixels (non-missing). 

3162902 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

5 

52834 

0.42120 

2 

22824 

0.18196 

4 

4506 

0.03592 

1 

35286 

0.28131 

9 

9986 

0.07961 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

5 

77195 

0.860405 

2 

33574 

0.760410 

4 

9158 

0.304761 

1 

50619 

0.801754 

9 

19588 

0.740147 


Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

5 

5688 

2281 

4370 

9.289 

0.8549 

2 

3569 

1944 

2930 

6.395 

0.7833 

4 

1951 

178 

1760 

2.310 

0.4257 

1 

4574 

2681 

3524 

7.714 

0.8255 

9 

732 

2656 

560 

13.642 

0.9116 

Overall values, not area-weighted: 

16514 2681 7596 

0.8227 


LEGEND 

1: Forest; 


2: Forest Loss; 


4: Forest Gain; 


5: Human Use; 


T2LXxffll.wpd - 078Leb98 

9: Water 














































NHi 



An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 



Tensas River Basin - Backswamp Analysis Zone 2 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

5 types found. 

2616 pixels (non-missing). 

26094 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

5 

950 

0.36315 

2 

26 

0.00994 

4 

124 

0.04740 

1 

115 

0.04396 

9 

1401 

0.53555 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

5 

1197 

0.729323 

2 

37 

0.027027 

4 

264 

0.291667 

1 

214 

0.392523 

9 

2696 

0.918769 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

5 

184 

133 

145 

5.163 

0.7305 

2 

23 

2 

23 

1.130 

0.0000 

4 

51 

20 

47 

2.431 

0.4113 

1 

33 

26 

27 

3.485 

0.6696 

9 

12 

1371 

9 

116.750 

0.9893 

Overall values, not area-weighted: 

303 1371 8.634 0.8440 


T2LXxffll2.wpd - 078Leb98 


LEGEND 

1: Forest; 2: Forest Loss; 4: Forest Gain; 5: Human Use; 9: Water 





























































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 



Tensas River Basin - Backswamp Analysis Zone 3 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

5 types found. 

7005 pixels (non-missing). 

233235 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

5 

5480 

0.78230 

1 

522 

0.07452 

2 

478 

0.06824 

9 

225 

0.03212 

4 

300 

0.04283 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

5 

7390 

0.905683 

1 

1020 

0.503922 

2 

1030 

0.416505 

9 

503 

0.493042 

4 

667 

0.560720 


Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

5 

685 

1296 

531 

8.000 

0.8279 

1 

104 

91 

83 

5.019 

0.7414 

2 

122 

43 

100 

3.918 

0.7176 

9 

29 

100 

20 

7.759 

0.8756 

4 

60 

189 

54 

5.000 

0.7700 

Overall values, not area-weighted: 

1000 1296 7.005 

0.8130 


T2LXxffII3.wpd - 078Leb98 


1. Forest, 2: Forest Loss; 4: Forest Gain; 5: Human Use; 9: Water 


















































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 






Tensas River Basin - Backswamp Analysis Zone 4 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

5 types found. 

33623 pixels (non-missing). 

452883 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

5 

19018 

0.56562 

2 

6909 

0.20548 

4 

879 

0.02614 

1 

6551 

0.19484 

9 

266 

0.00791 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

5 

26988 

0.913739 

2 

10140 

0.781262 

4 

1868 

0.328694 

1 

10236 

0.777354 

9 

479 

0.455115 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

5 

1558 

2279 

1104 

12.207 

0.8935 

2 

911 

1173 

703 

7.584 

0.8136 

4 

320 

46 

271 

2.747 

0.5290 

1 

652 

333 

469 

10.048 

0.8773 

9 

84 

35 

69 

3.167 

0.6165 

Overall values, not area-weighted: 

3525 2279 9.538 0.8622 


T2LXxffll4.wpd - 078Leb98 


LEGEND 

1: Forest; 2: Forest Loss; 4: Forest Gain; 5: Human Use; 9: Water 



























































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 



Tensas River Basin - Backswamp Analysis Zone 5 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

5 types found. 

23173 pixels (non-missing). 

540827 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

5 

6798 

0.29336 

2 

3704 

0.15984 

1 

11259 

0.48587 

4 

551 

0.02378 

9 

861 

0.03716 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

5 

9827 

0.905973 

2 

4550 

0.827692 

1 

15566 

0.926057 

4 

997 

0.368104 

9 

1349 

0.607858 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

5 

694 

2010 

526 

9.795 

0.8601 

2 

633 

300 

506 

5.852 

0.7643 

1 

1119 

2688 

874 

10.062 

0.8595 

4 

201 

24 

168 

2.741 

0.4791 

9 

159 

89 

120 

5.415 

0.7573 

Overall values, not area-weighted: 

2806 2688 8.258 0.8316 


LEGEND 


T2LXxffl!5.wpd - 078Leb98 


1: Forest; 


2: Forest Loss; 


4: Forest Gain; 


5: Human Use; 


9: Water 

























































Tensas River Basin - Backswamp Analysis Zone 6 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

5 types found. 

2259 pixels (non-missing). 

62721 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

5 

214 

0.09473 

4 

71 

0.03143 

1 

1717 

0.76007 

9 

97 

0.04294 

2 

160 

0.07083 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

5 

162 

0.746914 

4 

79 

0.265823 

1 

1758 

0.883959 

9 

127 

0.299213 

2 

220 

0.572727 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

5 

65 

19 

54 

3.292 

0.5140 

4 

49 

6 

48 

1.449 

0.0845 

1 

330 

139 

258 

5.203 

0.7490 

9 

59 

11 

56 

1.644 

0.2474 

2 

43 

22 

34 

3.721 

0.6875 

Overall values, not area-weighted: 

546 136 4.137 0.6799 


T2LXxffll6.wpd - 078Leb98 


LEGEND 


1: Forest; 


2: Forest Loss; 


4: Forest Gain; 


5: Human Use; 


9: Water 




































































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 



Tensas River Basin - Backswamp Analysis Zone 7 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

5 types found. 

3266 pixels (non-missing). 

43902 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

5 

646 

0.19780 

4 

188 

0.05756 

1 

1992 

0.60992 

2 

367 

0.11237 

9 

73 

0.02235 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

5 

781 

0.706786 

4 

278 

0.370504 

1 

2378 

0.890664 

2 

520 

0.650000 

9 

146 

0.534247 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

5 

130 

44 

95 

4.969 

0.7152 

4 

72 

23 

63 

2.611 

0.4734 

1 

265 

498 

204 

7.517 

0.8183 

2 

81 

76 

66 

4.531 

0.6948 

9 

12 

23 

8 

6.083 

0.7534 

Overall values, not area-weighted: 

560 498 5.832 0.7627 


LEGEND 


T2LXxffll7.wpd - 078Leb98 


1: Forest; 


2: Forest Loss; 


4: Forest Gain; 


5: Human Use; 


9: Water 





























































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 



Tensas River Basin - Backswamp Analysis Zone 8 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

5 types found. 

20543 pixels (non-missing). 

421657 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

2 

4544 

0.22119 

1 

5872 

0.28584 

5 

4679 

0.22777 

4 

760 

0.03700 

9 

4688 

0.22820 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

2 

6077 

0.726181 

1 

8188 

0.693942 

5 

6824 

0.709115 

4 

1620 

0.211728 

9 

9057 

0.814066 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

2 

988 

938 

861 

4.599 

0.6912 

1 

1135 

860 

904 

5.174 

0.7301 

5 

848 

305 

728 

5.518 

0.7459 

4 

397 

22 

377 

1.914 

0.2421 

9 

281 

2551 

236 

16.683 

0.9185 

Overall values, not area-weighted: 

3649 2551 5.630 0.7500 


T2LXxffll8.wpd - 078Leb98 


LEGEND 

1: Forest; 2: Forest Loss; 4: Forest Gain; 5: Human Use; 9: Water 






























































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 


Tensas River Basin - Backswamp Analysis Zone 9 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

5 types found. 

32976 pixels (non-missing). 

670510 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

2 

6840 

0.20742 

1 

7172 

0.21749 

5 

14994 

0.45469 

9 

2217 

0.06723 

4 

1753 

0.05316 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

2 

11575 

0.748855 

1 

11057 

0.700009 

5 

23820 

0.809908 

9 

4481 

0.561928 

4 

3726 

0.273484 


Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

2 

844 

1944 

711 

8.104 

0.8266 

1 

1146 

435 

907 

6.258 

0.7896 

5 

1608 

1974 

1272 

9.325 

0.8533 

9 

227 

464 

156 

9.767 

0.8836 

4 

775 

40 

691 

2.262 

0.4278 

Overall values, not area-weighted: 

4600 1974 7 169 

0.8133 


LEGEND 

1: Forest; 


2: Forest Loss; 


T2LXxffll9.wpd - 078Leb98 

4: Forest Gain; 5: Human Use; 9: Water 





































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 


103 


Tensas River Basin - Forest Change Analysis 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

5 types found. 

1043907 pixels (non-missing). 

2256441 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

5 

660978 

0.63318 

2 

147836 

0.14162 

4 

19409 

0.01859 

1 

202203 

0.19370 

9 

13481 

0.01291 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

5 

1362552 

0.931209 

2 

330052 

0.789288 

4 

60144 

0.272363 

1 

435798 

0.852767 

9 

33600 

0.595476 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

5 

1387 

595999 

1086 

476.552 

0.9975 

2 

5047 

21183 

4064 

29.292 

0.9582 

4 

6209 

196 

5326 

3.126 

0.5763 

1 

3220 

99871 

2324 

62.796 

0.9819 

9 

943 

3006 

731 

14.296 

0.9140 

Overall values, not area-weighted: 

16806 595999 62.115 0.9800 


T2LFor.wpd -078Leb98 


LEGEND 

1: Forest; 2: Forest Loss; 4: Forest Gain; 5: Human Use; 9: Water 





























































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 


Tensas River Basin - Forest Change Analysis Zone 2 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pivpl Analyzer 

5 types found. 

15559 pixels (non-missing). 

13349 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

5 

12776 

0.82113 

4 

473 

0.03040 

2 

209 

0.01343 

1 

503 

0.03233 

9 

1598 

0.10271 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

5 

25877 

0.941415 

4 

1397 

0.342162 

2 

683 

0.218155 

1 

1397 

0.437366 

9 

3413 

0.850864 


Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

5 

36 

12554 

21 

354.889 

0.9970 

4 

102 

56 

80 

4.637 

0.7230 

2 

81 

14 

64 

2.580 

0.5742 

1 

71 

88 

54 

7.085 

0.8410 

9 

9 

1574 

5 

177.556 

0.9956 

Overall values, not area-weighted: 

299 12554 52.037 

0.9778 


LEGEND 

1: Forest; 


2: Forest Loss; 


T2LForZ2.wpd - 078Leb98 

4: Forest Gain; 5: Human Use; 9: Water 













































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 



Tensas River Basin - Forest Change Analysis Zone 3 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

5 types found. 

126076 pixels (non-missing). 

115730 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

5 

118966 

0.94361 

2 

3140 

0.02491 

1 

2210 

0.01753 

4 

1419 

0.01126 

9 

341 

0.00270 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

5 

240508 

0.962758 

2 

9303 

0.321187 

1 

5979 

0.465295 

4 

4581 

0.220912 

9 

936 

0.444444 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

5 

99 

118759 

89 

1201.677 

0.9990 

2 

896 

199 

783 

3.504 

0.6325 

1 

317 

229 

253 

6.972 

0.8154 

4 

584 

195 

537 

2.430 

0.4355 

9 

50 

121 

40 

6.820 

0.8358 

Overall values, not area-weighted: 

1946 118759 64.787 0.9799 


T2LForZ3.wpd - 078Leb98 


LEGEND 

1: Forest; 2: Forest Loss; 4: Forest Gain; 5: Human Use; 9: Water 






















































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 


Tensas River Basin - Forest Change Analysis Zone 4 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Res ults of Pixel Analyzer 

5 types found. 

256864 pixels (non-missing). 
235939 pixels coded as missing. 


Data Code 


Pixel Count 


Pixel Percent 


190676 


0.74232 


34739 


0.13524 


26983 


0.10505 


3765 


0.01466 


701 


0.00273 


Number of edges and percent of same-type edges 


Data code 


Number edges 


390435 


0.946759 


77568 


0.786497 


60100 
1769 
1943 

Patch Statistics 


0.776123 

0.242671 

0.387545 


Data code 


Number 

patches 

Largest 

patch 

N patches 
<5 cells 

216 

187267 

163 

1204 

18102 

986 

645 

11243 

440 

1292 

38 

1080 

139 

113 

117 


Avg patch 
size 


Overall values, not area-weighted: 

3496 


Proportion 

5 


187267 


73.474 


LEGEND 

1: Forest; 


0.9826 

T2LForZ4.wpd - 078Leb98 


2: Forest Loss; 


4: Forest Gain; 


5: Human Use; 9: Water 




























An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 




Tensas River Basin - Forest Change Analysis Zone 5 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

5 types found. 

171505 pixels (non-missing). 

409933 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

2 

30141 

0.17574 

5 

83380 

0.48617 

1 

54148 

0.31572 

4 

2487 

0.01450 

9 

1349 

0.00787 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

2 

64889 

0.850545 

5 

170793 

0.928662 

1 

111406 

0.920202 

4 

7090 

0.301410 

9 

3076 

0.443108 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

2 

576 

8090 

431 

52.328 

0.9756 

5 

165 

38714 

124 

505.333 

0.9977 

1 

350 

16950 

227 

154.709 

0.9928 

4 

756 

180 

644 

3.290 

0.5746 

9 

221 

120 

156 

6.104 

0.8013 

Overall values, not area-weighted: 

2068 38714 82.933 0.9846 


T2LForZ5.wpd - 078Leb98 


LEGEND 


1: Forest; 


2: Forest Loss; 


4: Forest Gain; 


5: Human Use; 


9: Water 



























































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 


Tensas River Basin - Wetland Restoration Analysis Zone 6 
LANDSTAT: Landscape Statistics Program, v. 7-94 


































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 



Tensas River Basin - Wetland Restoration Analysis Zone 7 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

5 types found. 

20405 pixels (non-missing). 

30431 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

1 

10572 

0.51811 

5 

6337 

0.31056 

9 

234 

0.01147 

2 

1731 

0.08483 

i 

4 

1531 

0.07503 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

1 

22433 

0.881246 

5 

13925 

0.756266 

9 

693 

0.285714 

2 

4528 

0.523410 

4 

4457 

0.329370 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

1 

138 

9851 

110 

76.609 

0.9834 

5 

90 

3781 

60 

70.411 

0.9858 

9 

77 

33 

66 

3.039 

0.5812 

2 

205 

631 

182 

8.444 

0.8458 

4 

345 

70 

278 

4.438 

0.7054 

Overall values, not area-weighted: 

855 9851 23.865 0.9470 


T2LForZ7.wpd - 078Leb98 


LEGEND 

1: Forest; 2: Forest Loss; 4: Forest Gain; 5: Human Use; 9: Water 































































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 



Tensas River Basin - Forest Change Analysis Zone 8 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

5 types found. 

221426 pixels (non-missing). 

224118 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

1 

56488 

0.25511 

2 

51239 

0.23140 

5 

103493 

0.46739 

4 

4261 

0.01924 

9 

5945 

0.02685 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

1 

120778 

0.860927 

2 

112422 

0.819075 

5 

216924 

0.898218 

4 

13786 

0.222690 

9 

13549 

0.698280 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

1 

898 

27145 

706 

62.904 

0.9794 

2 

1400 

20356 

1198 

36.599 

0.9659 

5 

546 

88833 

451 

189.548 

0.9936 

4 

1634 

101 

1469 

2.608 

0.4799 

9 

355 

2965 

298 

16.746 

0.9196 

Overall values, not area-weighted: 

4833 88833 45.815 0.9717 


T2LForZ8.wpd - 078Leb98 


1: Forest; 2: Forest Loss; 4: Forest Gain; 5: Human Use; 9: Water 























































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 


Tensas River Basin - Forest Change Analysis Zone 9 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

5 types found. 

200588 pixels (non-missing). 

505950 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

5 

134423 

0.67014 

2 

24496 

0.12212 

4 

6039 

0.03011 

1 

32586 

0.16245 

9 

3044 

0.01518 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

5 

280756 

0.900811 

2 

57829 

0.683602 

4 

18850 

0.265517 

1 

73665 

0.756302 

9 

8265 

0.462795 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

5 

413 

106774 

312 

325.479 

0.9964 

2 

1415 

3731 

1110 

17.312 

0.9315 

4 

1964 

109 

1679 

3.075 

0.5753 

1 

993 

6286 

715 

32.816 

0.9672 

9 

228 

729 

168 

13.351 

0.9067 

Overall values, not area-weighted: 

5013 106774 40.014 0.9697 


T2LForZ9.wpd - 078Leb98 


LEGEND 

1: Forest; 2: Forest Loss; 4: Forest Gain; 5: Human Use; 9: Water 






























































112 


An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 


1 ensas River Basin - Wetland Restoration Analysis 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

5 types found. 

1043906 pixels (non-missing). 

2256442 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

5 

652100 

0.62467 

2 

146646 

0.14048 

4 

30335 

0.02906 

1 

201389 

0.19292 

9 

13436 

0.01287 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

5 

1344920 

0.930219 

2 

327272 

0.789948 

4 

83052 

0.446022 

1 

433866 

0.853519 

9 

33469 

0.596343 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

5 

1420 

587999 

1108 

459.225 

0.9974 

2 

5034 

21183 

4058 

29.131 

0.9577 

4 

6100 

1574 

5227 

4.973 

0.7337 

1 

3207 

99710 

2320 

62.797 

0.9818 

9 

932 

3006 

722 

14.416 

0.9146 

Overall values, not area-weighted: 

16693 587999 62.536 

0.9801 


LEGEND 

1: Forest; 


2: Forest Loss; 


4: Forest Gain; 


5: Human Use; 


T2LWrpFl.wpd - 078Leb98 

9: Water 
















































Tensas River Basin - Wetland Restoration Analysis Zone 2 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

5 types found. 

15559 pixels (non-missing). 

13349 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

5 

12776 

0.82113 

4 

473 

0.03040 

2 

209 

0.01343 

1 

503 

0.03233 

9 

1598 

0.10271 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

5 

25877 

0.941415 

4 

1397 

0.342162 

2 

683 

0.218155 

1 

1397 

0.437366 

9 

3413 

0.850864 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

5 

36 

12554 

21 

354.889 

0.9970 

4 

102 

56 

80 

4.637 

0.7230 

2 

81 

14 

64 

2.580 

0.5742 

1 

71 

88 

54 

7.085 

0.8410 

9 

9 

1574 

5 

177.556 

0.9956 

Overall values, not area-weighted: 

299 12554 52.037 0.9778 


T2LWz2.wpd - 078Leb98 


LEGEND 

1: Forest; 2: Forest Loss; 4: Forest Gain; 5: Human Use; 9: Water 





















































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 



Tensas River Basin - Wetland Restoration Analysis Zone 3 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

5 types found. 

126076 pixels (non-missing). 

115730 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

5 

118781 

0.94214 

2 

3140 

0.02491 

1 

2210 

0.01753 

4 

1604 

0.01272 

9 

341 

0.00270 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

5 

240195 

0.962235 

2 

9303 

0.321187 

1 

5979 

0.465295 

4 

5008 

0.264577 

9 

936 

0.444444 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

5 

99 

118574 

89 

1199.808 

0.9990 

2 

896 

199 

783 

3.504 

0.6325 

1 

317 

229 

253 

6.972 

0.8154 

4 

588 

195 

537 

2.728 

0.5006 

9 

50 

121 

40 

6.820 

0.8358 

Overall values, not area-weighted: 

1950 118574 64.654 0.9799 


T2LWz3.wpd - 078Leb98 


1: Forest; 2: Forest Loss; 4: Forest Gain; 5: Human Use; 9: Water 



















































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 



Tensas River Basin - Wetland Restoration Analysis Zone 4 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

5 types found. 

256865 pixels (non-missing). 

235938 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

5 

184146 

0.71690 

2 

33844 

0.13176 

1 

26341 

0.10255 

4 

11848 

0.04613 

9 

686 

0.00267 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

5 

377554 

0.944336 

2 

75536 

0.787929 

1 

58623 

0.777971 

4 

28668 

0.629168 

9 

1901 

0.391899 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

5 

242 

180859 

181 

760.934 

0.9984 

2 

1188 

17264 

976 

28.488 

0.9543 

1 

641 

11112 

435 

41.094 

0.9715 

4 

1227 

1502 

1015 

9.656 

0.8634 

9 

130 

113 

108 

5.277 

0.7522 

Overall values, not area-weighted: 

3428 180859 74.931 0.9830 


T2LWz4.wpd - 078Leb98 


LEGEND 


1: Forest; 


2: Forest Loss; 


4: Forest Gain; 


5: Human Use; 


9: Water 



































































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 




Tensas River Basin - Wetland Restoration Analysis Zone 5 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

5 types found. 

171511 pixels (non-missing). 

409927 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

2 

30119 

0.17561 

5 

82039 

0.47833 

1 

54134 

0.31563 

4 

3869 

0.02256 

9 

1350 

0.00787 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

2 

64831 

0.851013 

5 

168118 

0.927456 

1 

111379 

0.920227 

4 

9945 

0.481750 

9 

3079 

0.442676 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

2 

568 

8090 

424 

53.026 

0.9759 

5 

171 

34533 

128 

479.760 

0.9976 

1 

349 

16937 

226 

155.112 

0.9929 

4 

751 

1587 

643 

5.152 

0.7268 

9 

222 

120 

157 

6.081 

0.8007 

Overall values, not area-weighted: 

2061 34533 83.217 0.9846 


LEGEND 


T2LWz5.wpd - 078Leb98 


1: Forest; 


2: Forest Loss; 


4: Forest Gain; 


5: Human Use; 


9: Water 








































































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 



Tensas River Basin - Wetland Restoration Analysis Zone 6 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

5 types found. 

30904 pixels (non-missing). 

35048 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

2 

3294 

0.10659 

5 

8736 

0.28268 

1 

18088 

0.58530 

9 

208 

0.00673 

4 

578 

0.01870 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

2 

7270 

0.794360 

5 

18187 

0.909441 

1 

36335 

0.941764 

9 

510 

0.233333 

4 

1680 

0.252976 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

2 

134 

2233 

113 

24.582 

0.9502 

5 

38 

6204 

30 

229.895 

0.9958 

1 

148 

12910 

124 

122.216 

0.9896 

9 

99 

30 

93 

2.101 

0.3462 

4 

220 

54 

201 

2.627 

0.5000 

Overall values, not area-weighted: 

639 12910 48.363 0.9736 


T2LWz6.wpd - 078Leb98 


LEGEND 

1: Forest; 2: Forest Loss; 4: Forest Gain; 5: Fluman Use; 9: Water 

























































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 


Tensas River Basin - Wetland Restoration Analysis Zone 7 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzpr 

5 types found. 

20405 pixels (non-missing). 

30431 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

1 

10416 

0.51046 

5 

5570 

0.27297 

9 

207 

0.01014 

2 

1448 

0.07096 

4 

2764 

0.13546 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

1 

22018 

0.888364 

5 

12252 

0.745674 

9 

618 

0.266990 

2 

3833 

0.504305 

4 

7007 

0.549451 


Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

1 

120 

9786 

100 

86.800 

0.9847 

5 

91 

3780 

58 

61.209 

0.9847 

9 

74 

33 

65 

2.797 

0.5314 

2 

210 

620 

188 

6.895 

0.8004 

4 

307 

1315 

251 

9.003 

0.8538 

Overall values, not area-weighted: 

802 9786 25.443 

0.9493 


LEGEND 

1: Forest; 


2: Forest Loss; 


T2LWz7.wpd - 078Leb98 

4: Forest Gain; 5: Human Use; 9: Water 












































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 


Tensas River Basin - Wetland Restoration Analysis Zone 8 
LANDSTAT: Landscape Statistics Program, v. 7-94 


Results of Pixel Analyzer 

5 types found. 

221426 pixels (non-missing). 

224118 pixels coded as missing. 

Data Code 

Pixel Count 

Pixel Percent 

1 

56488 

0.25511 

2 

51239 

0.23140 

5 

103493 

0.46739 

4 

4261 

0.01924 

9 

5945 

0.02685 

Number of edges and percent of same-type edges 

Data code 

Number edges 

Same-type percentage 

1 

120778 

0.860927 

2 

112422 

0.819075 

5 

216924 

0.898218 

4 

13786 

0.222690 

9 

13549 

0.698280 

Patch Statistics 

Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

Avg patch 
size 

Proportion 

5 

1 

898 

27145 

706 

l 

62.904 

0.9794 

2 

1400 

20356 

1198 

36.599 

0.9659 

5 

546 

88833 

451 

189.548 

0.9936 

4 

1634 

101 

1469 

2.608 

0.4799 

9 

355 

2965 

298 

16.746 

0.9196 

Overall values, not area-weighted: 

4833 88833 45.815 0.9717 


T2LWz8.wpd - 078Leb98 


LEGEND 

1: Forest; 2: Forest Loss; 4: Forest Gain; 5: Human Use; 9: Water 



































































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 


Tensas River Basin - Wetland Restoration Analysis Zone 9 
LANDSTAT: Landscape Statistics Program, v. 7-94 

Results of Pixel Analy7er 

5 types found. 

200588 pixels (non-missing). 


Data Code 

Pixel Count 

Pixel Percent 

5 

134408 

0.67007 

2 

24496 

0.12212 

4 

6054 

0.03018 

1 

32586 

0.16245 

_9_ 

3044 

0.01518 

____ Number of edges and percent of same-type 

edges 

Data code 

Number edges 

Same-type percentage 

5 

280727 

0.900793 

2 

57829 

0.683602 

4 

18883 

0.266483 

1 

73665 

0.756302 

_9 

_ 8265 

0.462795 

_ Patch Statistics 



Data code 

Number 

patches 

Largest 

patch 

N patches 
<5 cells 

5 

415 

106754 

314 

2 

1415 

3731 

1110 

4 

1962 

109 

1676 

1 

993 

6286 

715 

9 

228 

729 

168 


Overall values, not area-weighted: 

5013 


Avg patch 
size 


Proportion 

5 


106754 


40.014 


LEGEND 

1: Forest; 


0.9697 

T2L.Wz9.wpd - 078Leb98 


2: Forest Loss; 


4: Forest Gain; 5: Human Use; 9: Water 


































An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 



Summary Statistics for water quality parameters from three water quality monitoring stations 
in the Tensas River Basin. 


Station 

Season 

Parameter 

N 

Mean 

Standard 

Deviation 

Maximum 

Median 

Minimum 

Clayton 

Fall 

Nitrogen 

7 

0.05 

0.059 

0.18 

0.02 

0.02 

Clayton 

Fall 

Phosphorus 

7 

0.12 

0.053 

0.23 

0.11 

0.08 

Clayton 

Spring 

Nitrogen 

9 

0.89 

0.523 

1.98 

0.85 

0.25 

Clayton 

Spring 

Phosphorus 

9 

0.46 

0.225 

0.89 

0.39 

0.24 

Clayton 

Summer 

Nitrogen 

13 

0.73 

0.802 

2.53 

0.26 

0.02 

Clayton 

Summer 

Phosphorus 

13 

0.24 

0.106 

0.44 

0.23 

0.03 

Clayton 

Winter 

Nitrogen 

12 

0.53 

0.456 

1.86 

0.34 

0.22 

Clayton 

Winter 

Phosphorus 

12 

0.44 

0.331 

1.26 

0.38 

0.09 

Tendal 

Fall 

Nitrogen 

7 

0.43 

0.938 

2.55 

0.02 

0.02 

Tendal 

Fall 

Phosphorus 

7 

0.55 

0.216 

0.96 

0.54 

0.22 

Tendal 

Spring 

Nitrogen 

9 

0.88 

0.775 

2.50 

0.57 

0.02 

Tendal 

Spring 

Phosphorus 

9 

0.53 

0.261 

1.07 

0.44 

0.24 

Tendal 

Summer 

Nitrogen 

14 

0.98 

1.547 

5.90 

0.38 

0.02 

Tendal 

Summer 

Phosphorus 

14 

0.43 

0.276 

1.04 

0.29 

0.18 

Tendal 

Winter 

Nitrogen 

12 

0.56 

0.586 

2.25 

0.45 

0.01 

Tendal 

Winter 

Phosphorus 

12 

0.49 

0.290 

1.10 

0.45 

0.00 

Winnsboro 

Fall 

Nitrogen 

4 

0.22 

0.400 

0.82 

0.02 

0.02 

Winnsboro 

Fall 

Phosphorus 

4 

0.16 

0.102 

0.31 

0.12 

0.09 

Winnsboro 

Spring 

Nitrogen 

6 

0.83 

0.615 

1.63 

0.72 

0.21 

Winnsboro 

Spring 

Phosphorus 

6 

0.45 

0.230 

0.72 

0.42 

0.10 

Winnsboro 

Summer 

Nitrogen 

11 

1.00 

0.857 

2.54 

0.61 

0.01 

Winnsboro 

Summer 

Phosphorus 

11 

0.33 

0.210 

0.85 

0.28 

0.06 

Winnsboro 

Winter 

Nitrogen 

9 

0.43 

0.209 

0.66 

0.52 

0.08 

Winnsboro 

Winter 

Phosphorus 

9 

0.42 

0.313 

1.13 

0.33 

0.13 


















An Ecological Assessment of the Louisiana Tensas River Basin: Appendix 





Results ofWilcoxon Rank Sum Test for Determining differences between water quality monitoring stations 


Compare Station to Station 

Parameter 

Season 

Significantly Different 

Tendal 

Clayton 

Total N itrogen 

All Combined 

No 

Tendal 

Clayton 

Total Phosphorus 

All Combined 

Yes 

Tendal 

Winnsboro 

Total N itrogen 

All Combined 

No 

Tendal 

Winnsboro 

Total Phosphorus 

All Combined 

Yes 

Clayton 

Winnsboro 

Total Nitrogen 

All Combined 

No 

Clayton 

Winnsboro 

Total Phosphorus 

All Combined 

No 

Clayton 

Winnsboro 

Total N itrogen 

Spring 

No 

Clayton 

Winnsboro 

Total N itrogen 

Summer 

No 

Clayton 

Winnsboro 

Total N itrogen 

Fall 

No 

C lay ton 

Winnsboro 

Total N itrogen 

Winter 

No 

Tendal 

Clayton 

Total N itrogen 

Spring 

No 

Tendal 

Clayton 

Total N itrogen 

Summer 

No 

Tendal 

Clayton 

Total N itrogen 

Fall 

No 

Tendal 

Clayton 

Total Nitrogen 

Winter 

No 

Tendal 

Winnsboro 

Total N itrogen 

Spring 

No 

Tendal 

Winnsboro 

Total N itrogen 

Summer 

No 

Tendal 

Winnsboro 

Total N itrogen 

Fall 

No 

Tendal 

Winnsboro 

Total N itrogen 

Winter 

No 

Clayton 

Winnsboro 

Total Phosphorus 

Spring 

No 

C lay ton 

Winnsboro 

Total Phosphorus 

Summer 

No 

Clayton 

Winnsboro 

Total Phosphorus 

Fall 

No 

Clayton 

Winnsboro 

Total Phosphorus 

Winter 

No 

Tendal 

Clayton 

Total Phosphorus 

Spring 

No 

Tendal 

C lay ton 

Total Phosphorus 

Summer 

Yes 

Tendal 

Clayton 

Total Phosphorus 

Fall 

Yes 

Tendal 

Clayton 

Total Phosphorus 

Winter 

No 

Tendal 

Winnsboro 

Total Phosphorus 

Spring 

No 

Tendal 

Winnsboro 

Total Phosphorus 

Summer 

No 

Tendal 

Winnsboro 

Total Phosphorus 

Fall 

Yes 




































































An Ecological Assessment of the Louisiana Tensas River Basin: Acknowledgements 



Acknowledgements 


The authors wish to express their thanks to the 
authors of the U.S. EPA Report, "An Ecological 
Assessment of the United States Mid-Atlantic Re¬ 
gion: A Landscape Atlas," for the extensive use of 
Chapters 1 and 2 from that document. The citation 
for the above report is as follows: 

Jones, K.B., K.H. Riitters, J.D. Wickham, R.D 
Tankersley, Jr., R.V. O'Neill, D.J. 

Chaloud, E.R. Smith, and A.C. Neale, 

1997. An Ecological Assessment of 
the United States Mid-Atlantic Region: 

A Landscape Atlas U.S. EPA J ORD, 
EPA/600/R-97/130 

The authors also would like to acknowledge the 
following people and their contributions to this docu¬ 
ment: Dr. Eugene Meier, Larinda Tervent, James E. 
Seals, and the U.S. EPA Gulf of Mexico Program, 
Kenneth Teague, U.S. EPA Region 6, Mike Adcock, 
Tensas River Basin Coordinator, Mark Swan, The 
Louisiana Nature Conservancy, Robert F. Carsel, 
U.S. EPA, NERL, Athens, GA, Jan R. Boydsten, 
Louisiana Dept, of Environmental Quality, Donna 
Sutton, Lockheed/Martin Corp., Dan Sahagun, ATA 
Corp., Deborah J. Chaloud, Don Ebert, Katie 
Feldman and Tyrone Roach, U.S. EPA, NERL, Las 
Vegas, NV. A special thanks goes to Pat Deliman 
for use of several of his photographs of the Tensas 
River Basin. 


Notice 

The purpose of this atlas is to show examples of how 
the principles of landscape ecology can be applied in 
a watershed-scale ecological assessment. The 
examples do not constitute a definitive assessment 
of ecological conditions in the Tensas River Basin. 
The EPA, through its Office of Research and 
Development (ORD), partially funded the research 
described here under U.S. EPA contract #68-C5- 
0065 to Lockheed/Martin Corporation. It has been 
peer reviewed by the EPA and approval for publica¬ 
tion. Mentions of trade names does not constitute 
endorsement or recommendation for use. 



























































LIBRARY OF CONGRESS 



1990s Classified Image, 
Land Cover 


Land Cover 
Forest 
Human Use 
Water 


0 006 249 507 8 


1970s Classified Image, 
Land Cover 







































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